11-7= 9+30= 26-6= 46+4+2=
75+20= 14-9= 90-10= 88-8+6=
9+9= 58-50= 15-6= 23+(49-9)=
13-4=□-□=□-□=□-□
□○□=□(个)
9×3.14= +÷= 36×= 728﹣299=
72÷0.4= 75×10%= 1÷×= 12.56÷6.28=