Bonjour

A = 7 + 3 (2x - 6)

A = 7 + 6x - 18

A = 6x - 11

B = 8x + (2x - 2) (3x + 1)

D = 8x + 6x² + 2x - 6x - 2

D = 6x² + 4x - 2

C = (3x * 5) (2 - 7x)

C = 15x (2 - 7x)

C = 30x - 105x²

C = - 105x² + 30x

D = (2 + 7x) (2 - 7x) - 5x (7x + 3)

D = 4 - 49x² - 35x² - 15x

D = - 84x² - 15x + 4.