Two point charges q and 4q are at x=0 and x=l, respectively, and free to move. A third charge is placed so that the entire three-charge system is in static equilibrium.

Abox contains 40 number tiles numbered 1 to 40. if a tile is drawn at random, what is the probability that the number drawn is a multiple of 3 or 4? find p(multiple of 4 or multiple of 5)