分数计算2/3+1/4+5/7=56/84+21/84+60/84=137/84
2/3+1/4+5/7=56/84+21/84+60/84=137/84
解:2/3+1/4+5/7=8/12+3/12+5/7=11/12+5/7=77/84+60/84=137/84=1又84分之53