Đáp án`+`Giải thích các bước giải:

 `4, 3/7 - 1/2x = 5/3`

`=> 1/2x = 3/7 - 5/3`

`=> 1/2x= (-26)/(21)`

`=> x=  (-26)/(21) : 1/2`

`=> x=  (-52)/(21)`

Vậy `x=  (-52)/(21)`

`8, 2/5x + 3/2=  5/4`

`=> 2/5x = 5/4 - 3/2`

`=> 2/5x = (-1)/4`

`=> x = (-1)/4 : 2/5`

`=> x= (-5)/8`

Vậy `x= (-5)/8`

`12, 2/3 - 4/7x = 1 - 1/2`

`=> 2/3 - 4/7x = 1/2`

`=> 4/7x = 2/3 -1 /2`

`=> 4/7x = 1/6`

`=> x=  1/6 : 4/7`

`=> x =7/(24)`

Vậy `x= 7/(24)`

`15, 3/5 - 1/4 = 1/(10)x - 1/2`

`=> 1/(10)x - 1/2 = 7/(20)`

`=> 1/(10)x = 7/(20) + 1/2`

`=> 1/(10)x = (17)/(20)`

`=> x=  (17)/(20) : 1/(10)`

`=> x=  (17)/2`

Vậy `x = (17)/2`

`18, 1 1/2x - 2/3 = 4 - 5/6`

`=> 3/2x - 2/3 = (19)/6`

`=> 3/2x = (19)/6 + 2/3`

`=> 3/2 x = (23)/6`

`=> x=  (23)/6 : 3/2`

`=> x =(23)/9`

Vậy `x=  (23)/9`

`21, 2 2/3 - 5/3x = 7/(10) x + 5/6`

`=> 8/3 - 5/3x = 7/(10) x + 5/6`

`=> 7/(10)x + 5/3x = 8/3 - 5/6`

`=> (71)/(30)x = (11)/6`

`=> x=  (11)/6 : (71)/(30)`

`=> x =(55)/(71)`

Vậy `x= (55)/(71)`

`24, (-5)/6 + 3x = 2/3 - 1/2x`

`=> 3x + 1/2x = 2/3 + 5/6`

`=> 7/2x = 3/2`

`=> x = 3/2 : 7/2`

`=> x = 3/7`

Vậy `x=  3/7`

`***`sharksosad