a) 128 - 3 . (x + 4) = 23
3 . (x + 4) = 128 - 23
3 . (x + 4) = 105
x + 4 = 105 : 3
x + 4 = 35
x = 35 - 4
x = 31
→ Vậy x = 31
b) 231 - (x - 6) = 1339 : 13
231 - (x - 6) = 103
x - 6 = 231 - 103
x - 6 = 128
x = 128 + 6
x = 134
→ Vậy x = 134
c) 2448 : [119 - (x - 6)] = 24
[119 - (x - 6)] = 2448 : 24
[119 - (x - 6)] = 102
(x - 6) = 119 - 102
(x - 6) = 17
x = 17 + 6
x = 23
→ Vậy x = 23
@Đậu Đậu