137+49=186
137-49=88
314+b=490, b=490-314 b=176
314-176=138
705-b=667, b=705-667, b=38
705+38=743
537+276=813
537-276=261
a+195=623, a=623-195, a=428
428-195=233
a-136=464, a=464-136, a=328
328+136=464
