The value of x is the number inside the parenthesis, so h(-4) gives x a value of -4.
The equation says when X is ≤ -4 use the first equation
So h(-4) = -1/2(x) -15
= -1/2(-4) -15
= 2 -15
= -13
When x = -2 (h(-2) ) use the 2nd equation:
h(-2) = 20-3x^2
=20-3(-2)^2
= 20-3(4)
=20-12
=8
Now you have -13 + 3(8)
= -13 + 24
=11
The answer should be 11