Решим уравнения:
x - 12 = 0
x = 12
25 + x = 25
x = 25 - 25
x = 0
x : 108 = 1
x = 108
y : 1 = 37
y = 37
x · 15 = 0
x = 0 : 15
x · 18 = 18
x = 18 : 18
x = 1
Ответ: x = 12; x = 0; x = 108; y = 37; x = 0; x = 1