Place knights, bishops, and at least one queen on a chess board such that no piece is on a square threatened by another piece. Try to maximize the expression NB/Q.
N = number of knights
B = number of bishops
Q = number of queens
I'll be working on this along with the rest of you, since I don't know for sure the maximum value. A quick attempt of mine gave a value of 45.
EDIT: New solution gives 48