5/7-1/6等于23/42。先通分,5/7,1/6通分后是30/42,7/42。原式=30/42-7/42=(30-7)/42=23/42
5/7-1/6=30/42-7/42=23/42
=(5*6)/(7*6)-(1*7)/(7*6)=30/42-7/42=23/42
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