Tìm x X+1/15=1/3 -2/7+4/7x=5/7 3/4:x-5/4=-1/2

Đáp án:

 `x+1/15=1/3`

`=>x=1/3-1/15`

`=>x=5/15-1/15`

`=>x=4/15`

Vậy `x=4/15`

____________

`-2/7+4/7x=5/7`

`=>4/7x=5/7-(-2/7)`

`=>4/7x=5/7+2/7`

`=>4/7x=1`

`=>x=1: 4/7`

`=>x=7/4`

Vậy `x=7/4`

______________

`3/4:x-5/4=-1/2`

`=>3/4:x=-1/2+5/4`

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

`=>3/4:x=3/4`

`=>x=3/4: 3/4`

`=>x=3/4. 4/3`

`=>x=1`

Vậy `x=1`