1) 5x + 4x – x = 128 2) 6x + 3x – 4 x = 105

a/5x+4x-x=128

<=>(5+4-1)x=128

<=>8x=128

<=>x=128/8

<=>x=16

Vậy x=16

b/6x+3x-4x=105

<=>(6+3-4)x=105

<=>5x=105

<=>x=105/5

<=>x=21

Vậy x=21