Câu `1:`

`a)` `5/4-(-3/16)`

`=5/4+3/16`

`=20/16+3/16`

`=23/16`

`b)` `7/3-(-1/4-5/12)`

`=7/3+1/4+5/12`

`=28/12+3/12+5/12`

`=36/12`

`=3`

`c)` `3/7+(-5/2). (-3/5)`

`=3/7+3/2`

`=6/14+21/14`

`=27/14`

`---`

Câu `2:`

`a)` `(-2/3):x=5/6`

`x=-2/3:5/6`

`x=-4/5`

Vậy `x=-4/5`

`b)` `1/2:x=-5/7-(-2/3)`

`1/2:x=-5/7+2/3`

`1/2:x=(-1)/21`

`x=1/2:(-1/21)`

`x=(-21)/2`

Vậy `x=(-21)/2`

`c)` `x-3/4=1/2`

`x=1/2+3/4`

`x=5/4`

Vậy `x=5/4`