Question

1+2分之1-6分之5+12分之7-20分之9+30分之11-42分之13+56分之15-72分之17=?(过程也要)

Answer 1

1 1/2-5/6 7/12-9/20 11/30-13/42 15/56-17/72=1 1/2-(1/2 1/3) (1/3 1/4)-(1/4 1/5) (1/5 1/6)-(1/6 1/7) (1/7 1/8)-(1/8 1/9)=1 1/2-1/2-1/3 1/3 1/4-1/4-1/5 1/5 1/6-1/6-1/7 1/7 1/8-1/8-1/9=1-1/9=8/9