25=10+15
17=13+4
42=21+21
36=34+2
28=17+11
64=100-36
72=73-1
41=59-18
31=72-70-29
23=36+30-43
87=55+32
64=72-8

25+17=42. 36+28=64. 41+31=72. 23+64=87
42-17=25. 28+36=64. 31+41=72. 64+23=87
42-25=17. 64-36=28. 72-31=41. 87-23=64
17+25=42 64-28=36. 72-41=31. 87-64=23