1又2分之1减6分之5加12分之7减20分之9加30分之11减42分之13加56分之15怎么简便计算???

Answer 1

3/2-5/6+7/12-9/20+11/30-13/42+15/56=(18-10+7)/12-(27-22)/60-(52-45)/168=15/12-5/60-7/168=14/12-7/168=7/6-1/24=27/24=9/8

Answer 2

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