To find the GCF, we list the factors of the coefficients and identify any common variable factors in the expressions.

The factors of $18$ are \[ 1,\quad 2,\quad 3,\quad 6,\quad 9,\quad 18. \]

The factors of $24$ are \[ 1,\quad 2,\quad 3,\quad 4,\quad 6,\quad 8,\quad 12,\quad 24. \]

The common factors of $18$ and $24$ are \[ 1,\quad 2,\quad 3,\quad 6. \]

The greatest of these common factors is $6.$

Now we look at the variable factors. Since $18$ has no variable and $24y$ contains $y,$ there are no variable factors in common.

Thus, the greatest common factor of $18$ and $24y$ is $6.$

To find the GCF, we list the factors of the coefficients and identify any common variable factors in the expressions.

The factors of $4$ are \[ 1,\quad 2,\quad 4. \]

The factors of $12$ are \[ 1,\quad 2,\quad 3,\quad 4,\quad 6,\quad 12. \]

The common factors of $4$ and $12$ are \[ 1,\quad 2,\quad 4. \]

The greatest of these common factors is $4.$

Now we look at the variable factors. Since $12$ has no variable and $4x$ contains $x,$ there are no variable factors in common.

Thus, $\textrm{GCF}(4x,12)=4.$

To find the GCF, we list the factors of the coefficients and identify any common variable factors in the expressions.

The factors of $49$ are \[ 1,\quad 7,\quad 49. \]

The factors of $14$ are \[ 1,\quad 2,\quad 7,\quad 14. \]

The common factors of $49$ and $14$ are \[ 1,\quad 7. \]

The greatest of these common factors is $7.$

Now we look at the variable factors. Both $49y$ and $14y$ contain $y.$

Thus, the greatest common factor of $49y$ and $14y$ is $7y.$

To find the GCF, we list the factors of the coefficients and identify any common variable factors in the expressions.

The factors of $4$ are \[ 1,\quad 2,\quad 4. \]

The factors of $2$ are \[ 1,\quad 2. \]

The common factors of $4$ and $2$ are \[ 1,\quad 2. \]

The greatest of these common factors is $2.$

Now we look at the variable factors. Both $4x$ and $2x$ contain $x.$

Thus, the greatest common factor of $4x$ and $2x$ is $2x.$

To find the GCF, we list the factors of the coefficients and identify any common variable factors in the expressions.

The factors of $6$ are \[ 1,\quad 2,\quad 3,\quad 6. \]

The factors of $12$ are \[ 1,\quad 2,\quad 3,\quad 4,\quad 6,\quad 12. \]

The factors of $30$ are \[ 1,\quad 2,\quad 3,\quad 5,\quad 6,\quad 10,\quad 15,\quad 30. \]

The common factors of $6,$ $12,$ and $30$ are \[ 1,\quad 2,\quad 3,\quad 6. \]

The greatest of these common factors is $6.$

Now we look at the variable factors. The expressions $6a,$ $12b,$ and $30b$ do not all share a variable factor.

Thus, the $\textrm{GCF}$ of $6a,$ $12b,$ and $30b$ is $6.$

To find the GCF, we list the factors of the coefficients and identify any common variable factors in the expressions.

The factors of $6$ are \[ 1,\quad 2,\quad 3,\quad 6. \]

The factors of $12$ are \[ 1,\quad 2,\quad 3,\quad 4,\quad 6,\quad 12. \]

The factors of $30$ are \[ 1,\quad 2,\quad 3,\quad 5,\quad 6,\quad 10,\quad 15,\quad 30. \]

The common factors of $6,$ $12,$ and $30$ are \[ 1,\quad 2,\quad 3,\quad 6. \]

The greatest of these common factors is $6.$

Now we look at the variable factors. The expressions $6x,$ $12x,$ and $30x$ all contain $x.$

Thus, the $\textrm{GCF}$ of $6x,$ $12x,$ and $30x$ is $6x.$