55-8= 47-9= 53-20= 83+7= 36+8=
47+50= 63-40= 24-7= 78+5= 20-20=
42+8-20= 67+20-30= 62+(16+4)=
14-9+76= 8+8+40= 13-(6+3)=
46+40-50= 51-(39-30)= 25+30-20=
微信扫码预览、分享更方便