a. -7 + (x - 4) - 11 = -2 + 2x
-7 + x + 4 - 11 = -2 + 2x
-22 + x = -2 + 2x
-22 + x - 2x = -2
x - 2x = -2 + 22
-x = -2 + 22
x = -20
Vậy ................
b. 30 - (2x - 1) + 5 = -3x + 7
30 - 2x + 1 + 5 = -3x + 7
36 - 2x = -3x + 7
36 - 2x + 3x = 7
-2x + 3x = 7 - 36
x = -29
Vậy ................
c. 3 . (x + 2) - 2 . (x - 7) = |-5|
3x + 6 - 2x + 14 = 5
x + 6 + 14 = 5
x + 20 = 5
x = 5 - 20
x = -15
Vậy ................