第1个回答 2013-06-01
1.(1)=1又3/7-(5/12+7/12)
=1又3/7-1
=3/7
(2)=3-1/56
=2又55/56
(3)=(5/8+3/8)+(9/17+8/17)
=1+1
=2
(4)=10/18+12/18-15/18
=7/18
(5)=12/15-7/15+4/9
=1/3+4/9
=3/9+4/9
=7/9
(6)=21/24+4/24-11/24
=14/24
=7/12
2.(1)X-3/5=1-3/5
X=1-3/5+3/5
X=1
(2)X-(5/6+1/2)=2/3
X-4/3=2/3
X=6/3
X=2