2х+7=70(4+2*х)
2х+7=280+140х
2х-140х=280-7
-138х=273
х=273 : (-138) = - 273/138 = -91/46
х= - 1 45/46
2* (- 1 45/46) +7 = 70*( 4+ 2* (-1 45/46))
2/1 * (-91/46) + 7 = 70* ( 4+ 2/1 *(-91/46))
-182/46 + 7 = 70 * ( 4 + (- 182/46))
-91/23 + 161/23 = 70 * ( 92/23 - 91/23)
70/23 = 70/1 * 1/23
3 1/23 = 3 1/23