Question

F(x) = 3x-7 and g(x) = -2x-6. Find (f o g)(4)

Answer 1

do you mean "find fg(4)" ?

if so that would be:
f(-2x-6)=3(-2x-6)-7
as g replaces x

then you replace x with 4 so
f(-2{4}-6)=3(-2{4}-6)-7
f(-6-6)=3(-8-6)-7
f(-12)=3(-14)-7
f(-12)=-11-7
f(-12)=-18