Question

2分之1加6分之5减去12分之7加20分之9减去30分之11加40分之13减去56分之12怎么算？

Answer 1

1/2+5/6-7/12+9/20-11/30+13/40-15/56
=1/2+(1/2+1/3)-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/5+1/8)-(1/7+1/8)
=1/2+1/2+1/4+1/4+1/6+1/5-1/7
=1+1/2+1/6+1/5-1/7
=1+30/60+10/60+12/60-1/7
=1+52/60-1/7
=1+13/15-1/7
=1+91/105-13/105
=1+78/105
=1又35分之26。