Ответ:
1. x = 2
2. x = 3
3. x = 5
Пошаговое объяснение:
1. 5(8x + 3) - 12 = 83
40x + 15 - 12 = 83
40x + 3 = 83
40x = 83 - 3
40x = 80
x = 2
2. 7(2x + 9) + 3x = 114
14x + 63 + 3x = 114
17x + 63 = 114
17x = 114 - 63
17x = 51
x = 3
3. 3(4x + 13) - 25 = 74
12x + 39 - 25 = 74
12x + 14 = 74
12x = 74 - 14
12x = 60
x = 5