Divide both the top and bottom numbers by $ \color{orangered}{ 2 } $.

Multiply $ \dfrac{25}{9} $ by $ y $ to get $ \dfrac{ 25y }{ 9 } $.

Step 1: Write $ y $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} \frac{25}{9} \cdot y & \xlongequal{\text{Step 1}} \frac{25}{9} \cdot \frac{y}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ 25 \cdot y }{ 9 \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 25y }{ 9 } \end{aligned} $$

Subtract $10$ from $ \dfrac{25y}{9} $ to get $ \dfrac{ \color{purple}{ 25y-90 } }{ 9 }$.

Step 1: Write $ 10 $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

Step 2: To subtract raitonal expressions, both fractions must have the same denominator.
We can create a common denominator by multiplying the second fraction by $\color{blue}{9}$.

$$ \begin{aligned} \frac{25y}{9} -10 & \xlongequal{\text{Step 1}} \frac{25y}{9} - \frac{10}{\color{red}{1}} = \frac{ 25y }{ 9 } - \frac{ 10 \cdot \color{blue}{ 9 }}{ 1 \cdot \color{blue}{ 9 }} = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ \color{purple}{ 25y } }{ 9 } - \frac{ \color{purple}{ 90 } }{ 9 }=\frac{ \color{purple}{ 25y-90 } }{ 9 } \end{aligned} $$