nhanh giúp mình được 0 ạa

`a) 25% - 1``1/2 - (-1/2)^2 + 0,25 : 1/12`

`= 1/4 - 3/2 - 1/4 + 1/4 xx 12`

`= 1/4 - 3/2 - 1/4 + 3`

`= -5/4 - 1/4 + 3`

`= -3/2 + 3`

`= 3/2`

`b) (-2)^3 . (-1)/(24) + (4/5 - 1,2) : 2/15`

`= (-2)^3 . (-1)/(24) + (4/5 - 12/10) : 2/15`

`= -8 . (-1)/24 + (-2)/5 : 2/15`

`= 1/3 + (-2)/5 xx 15/2`

`= 1/3 + (-3)`

`= -8/3`