mọi người ơi giúp e với heplllllllllll

`a)` `(4/15+7/12-19/20)*2,5+0,25`

`=(16+35-57)/(3*4*5)*5/2+1/4`

`=(-6*5)/(3*4*5*2)+1/4`

`=1/4+(-6*5)/(6*4*5)`

`=1/4-1/4`

`=0`

`b)` `15/34-1/3+19/34-1 5/7-2/3`

`=(15/34+19/34)-(1/3-2/3)-1 5/7`

`=34/34-3/3-1 5/7`

`=1-1-1 5/7`

`=-1 5/7`

`c)` `(1-2/3-0,75):(2 1/2-3/4-0,875)`

`=(1-2/3-3/4):(5/2-3/4-7/8)`

`=(12-8-9)/(3*4):(20-6-7)/8`

`=-5/(3*4)*8/7`

`=-(5*2*4)/(3*4*7)`

`=-10/21`

`d)` `(37/13+25/16):3/5-(9/16-15/13):3/5`

`=(37/13+25/16-9/16+15/13):3/5`

`=(52/13+16/16)*5/3`

`=(4+1)*5/3`

`=(5*5)/3`

`=25/3`

`e)` `(1-2/3-0,75):(2 1/2-3/4-0,875)` (câu c)

`h)` `(-3/5-2/9+1,25):(6-7 1/2-0,25)`

`=(-3/5-2/9+5/4):(6-15/2-1/4)`

`=(-108-40+225)/(4*5*9):(24-30-1)/4`

`=77/(4*5*9)*4/(-7)`

`=-(7*11*4)/(4*5*9*7)`

`=-11/(5*9)`

`=-11/45`