Пошаговое объяснение:
1) 5x + 2x = 4
7x = 4
x = 4/7
2) -3x - 4x = 5 - 4
-7x = 1
x = -1/7
3) -7 + 6 = -6x
-1 = -6x
x = 1/6
4) -11 + 2 = 8x - 5x
-9 = 3x
x = -3
