ssssssssssssssooooooooooooooossssssssssssss

Đáp án + Giải thích các bước giải:

` Bài  1`

`a) 42/49 + 56/84`

`= 6/7 + 2/3`

`= 18/21 + 14/21`

`= {18+14}/21`

`= 32/21`

_________________________

`b) 150/120 - 15/27`

`= 5/4 - 5/9`

`= 45/36 - 20/36`

`= {45-20}/36`

`= 65/36`

__________________________

`c) 48/32 xx 15/75`

`= 3/2 xx 1/5`

`= {3xx1}/{2xx5}`

`= 3/10`

__________________________

`d) 20/45 : 4`

`= 4/9 : 4/1`

`= 4/9 xx 1/4`

`= {4xx1}/{9xx4}`

`= 4/36`

`= 1/9`

__________________________

`e) 1 - 36/100`

`= 1 - 9/25`

`= 16/25`

`@long2010bad`