11-2= 13+10= 50-40= 20+5= 15-9-1=
15-5= 18-9= 80-70= 77-7= 14-5+20=
50+4= 65-60= 13-5= 16-8= 13-6+7=
40-30= 12+20= 14-5= 82-2= 50-30+8=
微信扫码预览、分享更方便