a) 3/4.x - 1/4 = 2. (x - 3) + 1/4.x
3/4.x- 1/4= 2.x- 6+ 1/4.x
3/4.x- 1/4= x.( 2+ 1/4)- 6
3/4.x- 1/4= x. 9/4- 6
⇒ 9/4.x- 6- 3/4.x+ 1/4=0
⇒ ( 9/4- 3/4).x- 6+ 1/4= 0
⇒ 3/2. x- 23/4= 0
⇒ 3/2.x= 23/4
x= 23/4: 3/2
x= 23/6
Vậy x= 23/6
b) 30%.x - x+ 5/6 = 1/3
( 30%- 1).x= 1/3- 5/6
( 3/10- 10/10).x= -3/6
-7/10.x= -1/2
x= -1/2: -7/10
x= -5/7
Vậy x= -5/7
c) l x l - 5/3/7 . l x l - 3/4 = 2. l x l . -8/7
( 1- $5$ $\frac{3}{7}$ ). lxl= -16/7. lxl
-31/7.lxl= -16/7.x
-31/7.x+ 16/7.x= 0
( -31/7+ 16/7).x= 0
⇒ x= 0
Vậy x= 0
Chúc học tốt! Nhớ kiểm tra lại nhé!