Уравнение

2x+7=70 * (4+2*X)

2 х+7=70 (4+2*х)

2 х+7=280+140 х

2 х-140 х=280-7

-138 х=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