A = (4x + 7) (x-2) - (3x + 1) (x-6)
=4x²-8x+7x-14 - (3x²-6x+x-6)
=4x²-8x+7x-14-3x²+6x-x+6
=x²+4x-8
B = 3x (x+2) - (4x - 3) (x+2)
=3x²+6x-(4x²+8x-3x-6)
=3x²+6x-4x²-8x+3x+6
= -x²+x+6
C = 7x - (4x + 1) (3x-2)
=7x-(12x²-8x+3x-2)
=7x-12x²+8x-3x+2
= -12x²+12x+2
D = (9x + 2) (2x-1) + 4x (3x + 7)
=18x²-9x+4x-2+12x²+28x
=30x²+23x-2