a) -5x+4x+6x²-7+x²+5x = 2x²+9x+(-7)
b) -2(-2a+3b)-3a(-4+3a-5b) = -9a²+15ab+8a+(-6b)
c) (-3+x)(-2x+3)-5 = -2x²+9x+(-14)
d) (4-2x)(-2x-3)-3x(3x+1) = -5x²+(-5x)+(-12)
