tính một cách hợp lý a)28/15+10/24-13/15+3 7/12 b) (-11/8).19/3.(-5/8) c) 12,5.(-5/7)+1,5.(-5/7) d)11/25.(-24,8)-11/25.75,2

`a.`

`28/15 + 10/24 - 13/15 + 3 7/12`

`= 28/15 + 5/12 -13/15 + 43/12`

`= (28/15-13/15) + (5/12 + 43/12)`

`= 15/15+48/12`

`= 1+4`

`=5`

`b.`

`(-11/8) . 19/3 + 19/3 . (-5/8)`

`= 19/3 . [ (-11/8) + (-5/8) ]`

`= 19/3 . (-16/8)`

`= 19/3 . (-2)`

`= -38/3`

`c.`

`12,5 . (-5/7) + 1,5 . (-5/7)`

`= (-5/7) . (12,5+1,5)`

`= (-5/7) . 14`

`= -70/7`

`= -10`

`d.`

`11/25 . (-24,8) -  11/25 . 75,2`

`= 11/25 . [ (-24,8) - 75,2 ]`

`= 11/25 . (-100)`

`= -44`