Giúp mình 4 câu này với ạ mình đang cần gấp

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

`= 3/5 : ((-1)/15 - 1/6) + 3/5 : ((-1)/3 - 16/15)`

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

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

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

`= 3/5. (-5)`

`= -3`

`b, sqrt(4/81). 27/8 - sqrt(0,49). 1/7`

`= 2/9. 27/8 - 7/10. 1/7`

`= 3/4 - 1/10`

`= 13/20`

`c, sqrt(0,01). sqrt(16/9) + 3sqrt(49) - 1/6sqrt(4)`

`= 1/10. 4/3 + 3. 7 - 1/6. 2`

`= 2/15 + 21 - 1/3`

`= 317/15 - 1/3`

`= 104/5`

`d, sqrt(16/81). 27/8 - sqrt(0,25). (-2)^2`

`= 4/9. 27/8 - 1/2. 4`

`= 3/2 - 2`

`= -1/2`

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