(х+3) / 7 = (2х - 1) / 5,
5 * (х + 3) = 7 * (2х - 1),
5х + 15 = 14х - 7,
5х - 14х = - 7 - 15,
- 9х = - 22,
Х = - 22 : (-9),
Х = 2 4/9 (2 целых четыре девятых)
Проверка:
(2 4/9 + 3) /7 = (2* 2 4/9 - 1) / 5,
(22/9+27/9) : 7 = (44/9 - 9/9) : 5,
49/9 : 7 = 35/9 : 5,
7:7 = 5:5,
1 =1