a)
4x + 15 = -5 | -5
4x = -20 | ÷ 4
x = -5
b)
2x + 7 = 4x - 3
2x - 4x = 3 + 7
-2x = 10 | ÷ 5
x = 5
c)
-2x(x + 3) + 4(2x + 3) = -6
-2x - 6 + 8x + 12 = -6
6x + 6 = -6 | -6
6x = -12 | ÷ 6
x = -2
d)
x - (7 + 2x) = 2(x - 1) + 1
x - 7 - 2x = 2x - 2 + 1
-6 = 3x | ÷ 3
x = -2
