1) X + 18 = 78X = 78 - 18X = 60
2) 21 - x = 15-x = 15 - 21-x = -6x = 6
3) x*13 = 91x = 91 / 13x = 7
4) x / 5 = 20x = 20 * 5x = 100
Ответ: x = 60, 6, 7, 100.
1) X + 18 = 78
X = 78 - 18
X = 60
2) 21 - x = 15
-x = 15 - 21
-x = -6
x = 6
3) x*13 = 91
x = 91 / 13
x = 7
4) x / 5 = 20
x = 20 * 5
x = 100
Ответ: x = 60, 6, 7, 100.