简便计算是先算2/3+5/62/3+5/6-4/7=9/6-4/7=3/2-4/7=13/14
先通分,再加减,最后能约分化简的就约分化为最简分数。2/3一4/7+5/6=28/42一24/42+35/42=39/42=13/14。
=2x14/42-4x6/42+35/42=(28-24+35)/42=39/42=13/14
2/3-4/7+5/6 = 28/42-24/42+35/42=(28-24+35)/42=39/42=13/14