1. (2022一下·大同期中) 口算

15-6=         13-5=          54-4=           11-7+6=

17-8=          11-6=          70-10=           14-9-2=

14-6=          75+4=         30+24=           20+30+40=

12-5=          18-9=          37+2=            40+60-70=