有简便法计算,20+19-18-17+16+15-14-13+12+11-10-9

2024-11-22 18:19:05
推荐回答(1个)
回答(1):

(20–10)+(19+11)+(18+12)(17+13)+(16+14)+(15-14)–9
=10+30+30+30+30+1–9
=10+120+1–9
=131-9
=122