just replace the value in the appropriate equation:
a) says f(-2)
so use the f equation above it and replace x with -2
f(x) = 3x-5 becomes f(-2) = 3x-5 =
3(-2)-5 = -6-5 = -11
for b use the equation for h and replace x with -5
so x^2 - 6 = -5^2 - 6 = -31
for c use the equation for g and replace x with (a+b)
-7x+3 =
-7(a+b)+3 = -7a-7b+3