Question 1000956
(f+g)(x)=2x+5+8x+2=10x+7.  Substituting (-9) and it is -90+7=-83
f(g(3)=start with g(3)=7.  f(7)=78.
or f(g(x))=10(x+4)+8=10x+40+8=10x+48=78, when x=3
or g(3)=7  f(7)=78
(f-g)(-8): 5x+5-6x-1=-x+4.  With (-8) for x, the answer is 12.