Chapter 1 - Introduction to Algebraic Expressions - Review Exercises: Chapter 1 - Page 75: 12

The answer is $-16$.

To evaluate, substitute the given value of the variable in the expression, then perform the operation: \begin{align} 9 - y^2 &= 9 - (-5)^2 &&\text{Substitute} \\ &= 9 - (25) &&\text{Square the number} \\ &= \color{red} {-16} &&\text{Evaluate} \end{align}