a) 6(-4x-5)+7
= -24x-30+7
= -24x-23
b) -5(6-4y)-5y
= -30+20y-5y
= 15y-30
c) 5(-2a+7)+3a
= -10a+35+3a
= -7a+35
d) 3b(5-6b)-9b
= 15b-18b²-9b
= -18b²+6b
A = 4x²+5x²
A = 9x²
B = 2x²-2x-5x²+4x
B = -3x²+2x
C = 3t-2-6t-3
C = -3t-5
D = 2x*3x*(1/2)
D = 6x²/2
D = 3x²