giúp với ạ nhanh gấp ạ

a)`4 4/5 . (5/12-5/6)+ 2/3²`

`=24.(-5/12)+2/9`

`=2.(-5)+2/9`

`=-10/1+2/9`

`=-90/9+2/9=-88/9`

b)`2/15.6/37+2/15.31/37+13/15`

`=2/15(6/37+31/37+1)`

`=2/16.2/1=1/4`

c)`8/21+(-3/20)+13/21-17/20+36/125`

`=(8/21+13/21)+[(-3/20)-17/20]+36/125`

`=1+(-1)+36/125=36/125`