1/5+3/8-2/9= 72/360+135/360-80/360= 127/360
1/4+2/9-5/36=9/36+8/36-5/36= 12/36= 1/3
3/4+4/5+1/20= 15/20+16/20+1/20= 32/20= 1×12/20= 1×3/5
3/4+5/12-1/9= 27/36+15/36-4/36= 38/36= 1×2/36= 1×1/18
4/15+2/5+7/10= 8/30+12/30+21/30= 41/30= 1×11/30
