5?-?6=16

52 - 36 = 16

Reason: Let the digits be a and b, so 5a - b6 = 16. (50 + a) - (10b + 6) = 16 → 44 + a - 10b = 16 → a - 10b = -28 → 10b - a = 28. With digits 0–9, the only solution is b = 3, a = 2, giving 52 - 36 = 16.