b)118-×+90=121
c)×-15-2=25

Răspuns:
b) 118 - x + 90 = 121
118 - x = 121 - 90 = 31
x = 118 - 31
x = 87
c) x - 15 - 2 = 25
x - 15 = 25 + 2 = 27
x = 27 + 15
x = 42