While expanding and adding the coefficients yields the correct answer, a significantly faster way is to realize that a+b+c+… is just the polynomial evaluated at x=1. This is the same as the original expression at x=1.
#9 : (5+3)\times(2-5) = (8)\times(-3) = -24
#10 : (1+3)^3 = 4^3 = 64
On test day it is now seconds instead of minutes.