Bonsoir,
-2x - 9 = 4(-x-4)
-2x - 9 = 4x - 16
-6x = -7
x = 7/6
7(-3x + 8) = -x - 24
-21x + 56 = -x - 24
-20x = -80
x = -80/-20
x = 4
-3/4 x - 4/5 = 6 - 2/5 x
-3/4 x + 2/5x = 6 + 4/5
-15/20 x + 8/20 x = 30/5 + 4/5
-7/20x = 34/5
-7x = (34×20)/5
-7x = 136
x = 136/-7