Thực hiện phép tính: A=1/4 + (-12/19) + 2/9 - 5/4 + 31/19 B=(-2)^3 .(3/4 - 0,25):( 2(1/4) - 1(1/6) )

`A = 1/4 + (-12/19) + 2/9 -5/4 + 31/19`

`A=  (1/4 - 5/4) + ( 31/19-12/19) + 2/9`

`A=  -4/4 + 19/19 + 2/9`

`A=  -1 +1+2/9`

`A=2/9`

`B = (-2)^3 . (3/4 - 0,25) : ( 2 1/4 - 1 1/6)`

`B = -8 . ( 3/4 - 1/4) : ( 9/4 - 7/6)`

`B = -8 . 2/4 : 13/12`

`B = -4 . 12/13`

`B = -48/13`

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`B = (-2)^3 . (3/4 - 0,25) : ( 2(1/4) - 1(1/6) )`

`B = -8 . (3/4 - 1/4) : ( 2/4 - 1/6)`

`B = -8 . 2/4 : ( 3/6 - 1/6)`

`B = -4 : 1/3`

`B = -12`