The expression below gives the cost, in dollars, of sending a letter to Spain: 2w + 1 Here, w is the letter's weight in ounces.

\overbrace{\:{\color{blue}2}\!\!\!{\underset{\underset{\Large\textrm{weight}}{\large\uparrow}}{w}}\!\!\!+{\color{red}1}\:}^{\large\textrm{total cost}}

The coefficient of w is the cost for each additional ounce of weight.

To illustrate:

  • If w=1 (we have a 1 -ounce letter), the cost is {\color{blue}2} \cdot 1 + {\color{red}1} = \[math]3.

  • If w=2 (we have a 2 -ounce letter), the cost is {\color{blue}2} \cdot 2 + {\color{red}1} = \[/math]5.

  • If w=3 (we have a 3 -ounce letter), the cost is {\color{blue}2} \cdot 3 + {\color{red}1} = \[math]7.

Note the following:

  • The number \color{blue}2 in this expression represents a unit rate. Each time we increase the letter's weight by 1 ounce, the cost increases by \color{blue}\[/math]2 .

  • There is also a base fee of \color{red}\[math]1 , which does not depend on the weight of the letter. We can think of this as the cost of sending a zero-ounce letter.

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The taxi fare, in dollars, charged by a particular cab company is given by the expression 6m+8, where m is the number of miles traveled. What do the constant term and the coefficient of m represent in this context?

EXPLANATION

The expression tells us that the cab company charges \[math]6 for each mile traveled, plus a "base fee" of \[/math]8.

  • The constant term is 8. We can think of this as the fee (in dollars) for traveling zero miles.

  • The coefficient of m is 6. This represents the fee (in dollars) charged for every mile traveled.

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The taxi fare, in dollars, charged by a particular cab company is given by the expression $5m+10$, where $m$ is the number of miles traveled.

What does the coefficient of $m$ represent in this context?

a
The fee for traveling zero miles is $\$5.$
b
The driver charges a $\$5$ tip.
c
The total fee for traveling $m$ miles is $5m$ dollars.
d
The cab company charges $\$5$ for traveling $10$ miles.
e
The taxi company charges $\$5$ for each mile traveled.

The taxi fare, in dollars, charged by a cab company is given by the expression $6m+8$, where $m$ is the number of miles traveled.

What does the constant term of the expression represent in this context?

a
The fee for traveling zero miles is $\$8.$
b
The total fee for traveling $m$ miles is $6m$ dollars.
c
The cab company charges $\$6$ for traveling $8$ miles.
d
The fee for traveling zero miles is $\$6.$
e
The driver charges a $\$6$ tip.

A recording studio charges musicians an initial fee of \[math]70 to record an album. The studio also charges an additional fee of \[/math]55 per hour. What expression gives the cost of recording an album in terms of the number of hours h?

EXPLANATION

If h is the number of hours used to record an album, and the studio charges an fee of \[math]55 per hour, then the cost for h hours must be 55h.

However, there is also a fixed fee for recording an album. This fee is \[/math]70. Consequently, the constant term of the expression should be 70.

Therefore, the expression that represents the total cost of recording an album is: 55 h+70

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A dance academy charges a fixed price of $\$20$ to use its facilities and $\$30$ per hour of instruction.

What expression gives the total cost, in dollars, of using the facilities for $h$ hours?

a
$50$
b
$30 h+20h$
c
$20 h+30$
d
$50h$
e
$30 h+20$

A pizzeria charges $\$15$ for a cheese pizza and $\$3$ for each topping.

What expression gives the total cost, in dollars, of a pizza with $n$ toppings?

a
$15n+3$
b
$15$
c
$3n+15$
d
$3n$
e
$15n+3n$

In many countries, a sales tax is charged whenever an individual or company makes a purchase. The tax is usually based on a certain percentage of the sale price.

For example, suppose a person purchases a bicycle for \[math] 200, and there is a sales tax of 5\%. How much is this tax, and what is the total cost of the bicycle?

To determine the amount of the tax the person must pay, we multiply 200 \times 5\% , as follows:

\begin{align} \mathrm{Tax} &= \[/math]200 \times 5\%\\[5pt] &= \[math]200 \times 0.05\\[5pt] &= \[/math]10 \end{align}

Therefore, the purchaser must pay a \[math]10 sales tax. This means that the total amount the person needs to pay for the bicycle is

\[/math]200 + \[math]10 = \[/math]210.

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At a grocery store, the price of a turkey is N dollars. However, there is also a 7\% sales tax.

What expression represents the total cost of a turkey after tax is applied?

EXPLANATION

The price before taxes of the turkey is N dollars.

The amount of tax is 7\% of the price of the turkey, or 0.07N.

Therefore, the expression that represents the total cost of the turkey after tax is:

N+0.07N

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Alice is buying a handbag. The price of a handbag is $P$ dollars, and Alice also has to pay a $20\%$ tax.

What expression represents the total cost, in dollars, of a handbag after tax is applied?

a
$P+2P$
b
$P+20$
c
$P+20P$
d
$P+0.2$
e
$P+0.2P$

Abbie is buying a car. The price of the car is $C$ dollars, and he also has to pay a $15\%$ tax.

What expression represents the total cost, in dollars, of the car after tax is applied?

a
$C + 0.15$
b
$C + 15$
c
$C + 15C$
d
$C + 0.15C$
e
$0.15C$

In a particular fast-food restaurant, a standard lunch consists of 2 hot dogs for H dollars each, 8 potato wedges for W dollars each, and 1 drink D dollars. Monica went to the fast-food restaurant to pick up lunch for her family, and the total bill was 5(2H + 8W + D) dollars. What does the factor 5 mean in this context?

EXPLANATION

Two hot dogs cost 2H dollars, eight potato wedges cost 8W dollars, and a drink costs D dollars. Thus, each standard lunch costs 2H + 8W + D dollars. Monica's bill comes to 5(2H + 8W + D) dollars, which is 5 times the cost of a single standard lunch. Thus, the factor 5 must be the total number of standard lunches that Monica purchased.

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A bouquet of flowers consists of $3$ roses, $4$ tulips and $5$ violets. The cost of one rose is $R$ dollars, the cost of one tulip is $T$ dollars and the cost of one violet is $V$ dollars. Max is purchasing some bouquets for a wedding, and his total bill comes to $8(3R + 4T+5V)$ dollars.

What does the factor $8$ mean in this context?

a
Max purchased $8$ bouquets in total
b
Each bouquet costs $\$8$
c
There are $8$ roses in total
d
Each bouquet costs $(3R+4T+5V)$ dollars
e
There are $8$ tulips in total

A pack of markers consists of $3$ black markers for $B$ dollars each, $2$ red markers for $R$ dollars each, and one green marker for $G$ dollars. Maya purchases some packs of markers, and her total bill comes to $4(3B + 2R + G)$ dollars.

What does the factor $4$ mean in this context?

a
Maya purchased $4$ packs in total
b
There are $4$ black markers in total
c
There are $4$ markers in total
d
Each pack costs $(3B + 2R + G)$ dollars
e
Each pack costs $\$4$
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