a)
5x - 7 = - 3x + 9
5x + 3x = 9 + 7
8x = 16
x = 16/8
x = 2
b)
7 - (3 + x) = - 5x
7 - 3 - x = - 5x
- x + 5x = 3 - 7
4x = - 4
x = - 4/4
x = - 1
c)
2 (5 - 3x) = 7
10 - 6x = 7
- 6x = 7 - 10
- 6x = - 3
x = 3/6
x = 1/3
d)
6 (4 - 5x) = - 5 (10 + 4x)
24 - 30x = - 50 - 20x
- 30x + 20x = - 50 - 24
- 10x = - 74
x = 74/10
x = 7,4
