Решите уравнения:
1)х + 20 = 5х
2)20*7 + 7х = 287
3)2( х + х+10) = 208

Пошаговое объяснение:

1) x + 20 = 5x

x - 5x = -20

-4x = -20

x = 5

2) 20*7 + 7x = 287

140 + 7x = 287

7x = 287 - 140

7x = 147

x = 21

3) 2(x + x + 10) = 208

2x + 2x + 20 = 208

4x + 20 = 208

4x = 208 - 20

4x = 188

x = 47