To get 51 using the numbers 8, 5, 6, and 7 exactly once each, you can use the following mathematical expression:
(8 x 6) - 7 + 5 = 51
How it works:
1. Multiply 8 by 6 to get 48: (8 x 6) = 48
2. Subtract 7 from 48 to get 41: 48 - 7 = 41
3. Add 5 to 41 to get 51: 41 + 5 = 51
Therefore, (8 x 6) - 7 + 5 = 51.