5+=8
3+=12
13+=35
-2=4
-13=15
-17=38
87-=42
72-=36
100-=29
23+33=
25+46=
32+66=
5×9=
6×9=
7×9=

+31=72-45
-28=14+14
16++36=78
1+12+23+34=
18+=37-
15+33-27+12=
-20=+20
100-12-23-34=