Let's break down the problem step by step. We have the following statement:
"The sum of a number, \( w \), and 9 is multiplied by -3, and the result is -15."
We can translate this into an equation:
\[ -3(w + 9) = -15 \]
Now, let's solve for \( w \).
- Divide both sides of the equation by -3 to eliminate the multiplication:
\[ w + 9 = \frac{-15}{-3} \]
This simplifies to:
\[ w + 9 = 5 \]
- Now, subtract 9 from both sides:
\[ w = 5 - 9 \]
This simplifies to:
\[ w = -4 \]
So, the number \( w \) is \( -4 \).