Question

6分之5-12分之7+20分之9-30分之11+42分之13要简算方法

Answer 1

5/6-7/12+9/20-11/30+13/42
=1/2+1/3-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7
=1/2+1/7
=7/14+2/14
=9/14