3/8-7/15x3/8=1x3/8-7/15x3/8=(1-7/15)x3/8=8/15x3/8=1/5
提取相同的因数3/8-7/15x3/8=1x3/8-7/15x3/8=(1-7/15)x3/8=8/15x3/8=1/5
8/9 10/11-(3/11 2/9) = 8/9-2/9 10/11-3/11 =2/3 7/11 =43/33 9/26 5/14-3/13 3/28 =9/26-3/13 5/14 3/28 =3/26