`( 1/2 - 13/14 ) : 5/7 - ( - 2/21 + 1/7 ) : 5/7`

`= - 3/7 : 5/7 - 1/21 : 5/7`

`= ( - 3/7 - 1/21 ) : 5/7`

`= - 10/21 . 7/5`

`= - 2/3`

`---`

`3/5 : ( - 1/15 - 1/6 ) + 3/5 : ( - 1/3 - 1 1/15 )`

`= 3/5 : ( - 7/30 ) + 3/5 : ( - 7/5 )`

`= 3/5 . ( - 30/7 ) + 3/5 . ( - 5/7 )`

`= 3/5 . ( - 30/7 - 5/7 )`

`= 3/5 . ( - 35/7 )`

`= 3/5 . ( - 5 )`

`= - 3`

`---`

`13 3/5 - ( 8 3/5 - 4 3/4 )`

`= 68/5 - ( 43/5 - 19/4 )`

`= 68/5 - 43/5 + 19/4`

`= 25/5 + 19/4`

`= 5 + 19/4`

`= 39/4`

`#`Nguyencanhthinh`#`
`*** Hoidap247`