4+=10
9+=18
7+=22
-8=2
-12=12
-13=8
20-=14
36-=28
44-=12
16+7=
75+28=
105-25=
1×1=
1×2=
1×3=

+23=35-7
9+=11+18
6++5=30
18+19+20+21=
24+=50-
21+17+35+24=
23-=32-
42-28+33-39=