5/6-2/3+1/8
=20/24-16/24+3/24
=4/24+3/24
=7/24
7/10+3/8-1/5
=28/40+15/40-8/40
=43/40-8/40
=35/40
=7/8
5/16+1/9+8/9
=5/16+(1/9+8/9)
=5/16+1
=1又5/6
6/11+7/8-6/11
=6/11-6/11+7/8
=0+7/8
=7/8
9/23+(14/23-9/20)
=9/23+14/23-9/20
=1-9/20
=11/20
9-8/17-9/17
=9-(8/17+9/17)
=9-1
=8
13/32-(3/4-3/8)
=13/32-3/8
=13/32-12/32
=1/32
3/13+6/7+10/13
=3/13+10/13+6/7
=1+6/7
=1又6/7
2-8/13-5/13
=2-(8/13+5/13)
=2-1
=1