Both shapes are split into $\color{red}4$ equal parts.

• The shape on the left represents one whole because all $4$ pieces are shaded.

• The shape on the right represents $\dfrac 1 4,$ because only $1$ part is shaded.

So the model represents:

\[ 1 - \dfrac 1 4 \]

The shape on the left has $\color{blue}4$ shaded pieces, and the object on the right has $\color{blue}1$ shaded piece. Therefore,

\[ 1 - \dfrac 1 4 = \dfrac{{\color{blue}{4}} - {\color{blue}{1}}}{{\color{red}{4}}} = \dfrac 3 4. \]

All four shapes are split into $\color{red}7$ equal parts.

• The first three shapes represent three wholes because all $\color{red}7$ pieces are shaded.

• The shape on the right represents $\dfrac{5}{\color{red}7},$ because only $5$ parts are shaded.

Therefore, the model represents:

\[ 3 - \dfrac 5 7 \]

We have $7+7+7-5 = \color{blue}16$ shaded pieces in total. Therefore,

\[ 3-\dfrac{5}{7} = \dfrac{{\color{blue}16}}{{\color{red}7}}. \]

The shape on the right is split into $\color{red}6$ equal parts. We can split the shape on the left into $\color{red}6$ equal parts as follows:

We have $6 - 2 = \color{blue}4$ shaded parts in total.

Therefore, \[ 1-\dfrac 2 6 = \dfrac{\color{blue}4}{\color{red}6}. \]

Hence, the missing number is $\color{blue}4.$

The shape on the right is split into $\color{red}9$ equal parts. We can split the first and second shapes on the left into $\color{red}9$ equal parts as follows:

We have $9 + 9 - 2=\color{blue}16$ shaded parts in total.

Therefore,

\[ 2 - \dfrac{2}{9} = \dfrac{\color{blue}16}{9}. \]

Therefore, the missing number is $\color{blue}16.$

Writing $2 - \dfrac{1}{5}$ as a visual fraction model, we get:

The shape on the right is split into $\color{red}5$ equal parts. We can split the other two shapes into $\color{red}5$ equal parts as follows:

We have $5 + 5 - 1 = \color{blue}9$ shaded parts in total.

Therefore,

\[ 2 - \dfrac{1}{5} = \dfrac{\color{blue}9}{\color{red}5} . \]

Writing $3 - \dfrac{1}{4}$ as a visual fraction model, we get:

The shape on the right is split into $\color{red}4$ equal parts. We can split the first, second and third shapes into $\color{red}4$ equal parts as follows:

We have $4 + 4 + 4 - 1 = \color{blue}11$ shaded parts in total.

Therefore,

\[ 3 - \dfrac{1}{4} = \dfrac{\color{blue}11}{\color{red}4} . \]