Đáp án:
Giải thích các bước giải:
Bài 1:
`a,2/5+9/15=2/5+3/5=5/5=1`
`b,2-7/9=18/9-7/9=11/9`
`c,2xx6/25=12/25`
`d,6/11:3/4=6/11xx4/3=8/11`
Bài 2:
`a,1/3xx2/5:2/7=1/3xx2/5xx7/2=7/15`
`b,5/2+2:1/3=5/2+2xx3=5/2+6=17/2`
`c,8/15:2/11+7/15:2/11`
`=8/15 xx11/2+7/15xx11/2`
`=11/2xx(8/15+7/15)=11/2`