Đáp án:
a) 3-4x+24+6x=x+27+3x
⇔ -4x + 6x - x - 3x = 27 - 3 - 24
⇔ -2x = 0
⇔ x = 0
b) 5-(6-x)=4(3-2x)
⇔ 5 - 6 + x = 12 - 8x
⇔ x + 8x = 12 - 5 + 6
⇔ 9x = 13
⇔ x = 13/9
c) 5(2x-3)-4(5x-7)=19-2(x+11)
⇔ 10x - 15 - 20x + 28 = 19 - 2x - 22
⇔ 10x - 20x + 2x = 19 - 22 + 15 - 28
⇔ -8x = -16
⇔ x = 2