Answer:
-15
Explanation:
When functions are "nested" like this (nested is not a math word; the mathy word is composed or composition) you need to start all the way on the inside.
f(g(-3))
means find g(-3) first, then put that answer into f.
g(x) = x - 7
g(-3) = -3 - 7
g(-3) = -10
We found g(-3) is -10, so now put -10 into f.
f(x) = 2x + 5
f(-10) = 2(-10) + 5
= -20 + 5
= -15