bài 1)
a)
`-7/25` . `11/13` + `-7/25` . `2/13` - `18/25`
=`-7/25` . ( `11/13` + `2/13`) - `18/25`
= `-7/25` . `1` - `18/25`
= `-7/25` - `18/25`
= `-1`
b) `5/7` .`1/3` - `5/7` . `1/4` - `5/7` . `1/12`
= `5/7` . ( `1/3` - `1/4` - `1/12`)
= `5/7` . ( `4/12` - `3/12` - `1/12`)
= `5/7` . 0
= `0`
c) 5 `2/5` . 4 `2/7` + 5 `2/5` . 5 `2/5`
= `27/5` . `30/7` + `40/7` . `27/5`
= `27/5` . ( `30/7` + `40/7`)
= `27/5` . 10
= `54`
d) 75% - 1 `1/2` + `0,5` : `5/12` - ( `-1/2`)²
= `3/4` - `3/2` + `1/2` : `5/12` - `1/4`
= `3/4` - `3/2` + `6/5` - `1/4`
= `-3/4` + `6/5` - `1/4`
= ( `-3/4` - `1/4`) + `6/5`
= `-1` + `6/5`
= `1/5`