It looks like you're trying to compute the composition of two functions \( f(x) \) and \( g(x) \) where:
- \( f(x) = x^2 + 8x + 15 \)
- \( g(x) = x + 5 \)
The notation \( f(g(x)) \) refers to the function \( f \) evaluated at \( g(x) \).
To compute \( f(g(x)) \):
1. First, substitute \( g(x) \) into \( f(x) \):
\[
g(x) = x + 5
\]
2. Now substitute \( g(x) \) into \( f(x) \):
\[
f(g(x)) = f(x + 5) = (x + 5)^2 + 8(x + 5) +