第1个回答 2012-08-27
(1)1又5/7+2/3+3又1/3+2又2/7
=(1又5/7+2又2/67)+(2/3+3又1/3)
=4+4
=8
(2)1又1/2-3/4+5/6
=3/4+5/6
=19/12
(3)9又3/5-2又1/6-3又5/6+2又2/5
=(9又3/5+2又2/5)-(2又1/6+3又5/6)
=12-6
=6
(4)3/7+7/8+4/7-1/8
=(3/7+4/7)+(7/8-1/8)
=1+3/4
=1又3/4
(5)2又3/5-(2/9+3/5)
=2又3/5-3/5-2/9
=2-2/9
=1又7/9
(6)2.8+1/2-1.6
=3.3-1.6
=1.7