!mk cần gấp! GIÚP VỚI!!

`a){-7}/12:0,25 + 3 1/4`

`={-7}/12 :1/4+13/4`

`={-7}/12 . 4+13/4`

`={-28}/12 + 13/4`

`={-28}/12+39/12`

`=11/12`

`b)({-19}/132+82/135)-({-19}/132+{-53}/135)`

`={-19}/132+82/135+19/132+53/135`

`=({-19}/132+19/132)+(82/135+53/135)`

`=0+135/135`

`=0+1`

`=1`

`c)49/71 . 21 1/7 - 49/71 . 11 1/7`

`=49/71 . (21 1/7-11 1/7)`

`=49/71 . [(21-11)+(1/7-1/7)]`

`=49/71 . (10+0)`

`=49/71 . 10`

`=490/71`

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`a)9/{-5}=36/x`

`->9x=-5.36`

`->9x=-180`

`->x=-180:9`

`->x=-20`

`-` Vậy : `x=-20.`

`b)2/3 . x+0,25=0,75`

`2/3 . x=0,75-0,25`

`2/3 . x=0,5`

`2/3 . x=1/2`

`x=1/2:2/3`

`x=1/2 . 3/2`

`x=3/4`

`-` Vậy : `x=3/4 .`

`#Sal_tSea`