Giúp mình với.......

`a)` `4x + 5/7x - 4x = (-15)/7`

`(4 +5/7 - 4).x = (-15)/7`

`5/7.x = (-15)/7`

`x = (-15)/7 : 5/7`

`x = (-15)/7 . 7/5``x =-3`

Vậy `x =-3`

`b)` `5/6x -3x - 5/6x = 21/20`

`(5/6 - 3 - 5/6).x = 21/20`

`-3.x = `21/20`

`x = 21/20 : (-3)`

`x = 21/20 . (-1/3)`

`x = -7/20`

Vậy `x = -7/20`

`c)` `1/2x + 3/5x - 1/3x = (-23)/25`

`(1/2 + 3/5 - 1/3).x = (-23)/25`

`(15/30 + 18/30 - 10/30).x = (-23)/25`

`23/30.x = (-23)/25`

`x = (-23)/25 : 23/30`

`x = (-23)/25 . 30/23`

`x = -6/5`

Vậy `x = -6/5`

`d)` `3/2x - 8/3x + 7/5x = (-7)/25`

`(3/2 - 8/3 + 7/5).x = (-7)/25`

`(45/30 - 80/30 + 42/30).x = (-7)/25`

`7/30.x = (-7)/25`

`x = (-7)/25 : 7/30`

`x = (-7)/25 . 30/7`

`x = -6/5`

Vậy `x = -6/5`