Bonjour,

A = 12a + 3(7a - 2)

A = 12a + 3*7a - 3*2

A = 12a + 21a - 6

A = 33a - 6

B = 15b - 4b(2 - 7)

B = 15b - 4b*2b + 4b*7

B = 15b - 8b² + 28b

B = 43b - 8b²

C = 16 - 6(3d - 4)

C = 16 - 6*3d + 6*4

C = 16 - 18d + 24

C = 40 - 18d

D = 9 - (y + 14)

D = 9 - y - 14

D = -5 - y