`a, x + 1/5 = 3/7 `$\\$ `x= 3/7 - 1/5`$\\$ `x= 15/35 - 7/35`$\\$ `x= 8/35`$\\$ Vậy `x=8/35`

 `b, x - 3/4 = 1/2 `$\\$ `x= 1/2 + 3/4`$\\$ `x= 2/4 + 3/4`$\\$ `x= 5/4`$\\$ Vậy `x= 5/4`

`c, 2/3 - x = 7/5`$\\$ `x= 2/3 - 7/5`$\\$ `x= 10/15 - 21/15`$\\$ `x= -11/15`$\\$ Vậy `x=-11/15` 

`d, 2/3 x = 1 3/5`$\\$ `2/3x=8/5`$\\$ `x=8/5:2/3`$\\$ `x=8/5 . 3/2`$\\$ `x=12/5`$\\$ Vậy `x =12/5`