Bonsoir
A = 3(2x - 6) - (3 - 5x)
= (3*2x + 3*(-6)) - (3 - 5x)
= 6x - 18 - 3 + 5x
= 11x - 21
B = (5 - 2y) - (-3y + 7)
= 5 - 2y + 3y - 7
= y - 2
C = 4(6 + z) + (z - 3)(2 - z)
= (4*6 + 4*z) + (z*2 + z*(-z) - 3*2 - 3*(-z))
= 24 + 4z + 2z - z² - 6 + 3z
= -z² + 9z + 18
D = (2t - 5)(3t + 2) - (t² + 6)
= (2t*3t + 2t*2 - 5*3t - 5*2) - (t² + 6)
= 6t² + 4t - 15t - 10 - t² - 6
= 5t² - 11t - 16
Voilà j'espère avoir pu t'aider ^^