tính a) 7/1x2/3-1/5 b) 5: (1/2+1/4)

`a) 7/1 xx 2/3 - 1/5`

`= ( 7/1 xx 2/3 ) - 1/5`

`= 14/3 - 1/5`

`= 70/15 - 3/15`

`= 67/15`

`b) 5: (1/2+1/4)`

`= 5 : ( 2/4 + 1/4 )`

`= 5 : 3/4`

`= 5 xx 4/3`

`= 20/3`