`a)`

`-5/9+x=4/9`

`x=4/9+5/9`

`x=1`

Vậy `x=1`

`b)`

`3/4+1/4x=-5/6`

`1/4x=-5/6-3/4`

`1/4x=-19/12`

`x=-19/12÷1/4`

`x=-19/12·4`

`x=-19/3`

Vậy `x=-19/3`

`c)`

`(2x-1)/3=(2-x)/(-2)`

`-2(2x-1)=3(2-x)`

`-4x+2=6-3x`

`-4x+3x=6-2`

`-x=4`

`x=-4`

Vậy `x=-4`

`d)`

`(2/5-3x)^2-1/5=4/25`

`(2/5-3x)^2=4/25+1/5`

`(2/5-3x)^2=9/25`

`Th1:`

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

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

`3x=-1/5`

`x=-1/5÷3`

`x=-1/5·1/3`

`x=-1/15`

`Th2:`

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

`3x=2/5+3/5`

`3x=1`

`x=1/3`

Vậy `x in {-1/15;1/3}`