7+=8
5+=13
16+=28
-2=7
-19=19
-15=23
45-=21
44-=18
80-=32
24+26=
38+44=
92+15=
4×4=
1×5=
2×5=

+28=72-32
-26=14+23
12++39=73
27+19+16+22=
28+=52-
13+22+33-38=
-35=+22
100-48-21-31=