According to the question, there are as many ping-pong balls in two small boxes as in one big box, so if there are x balls in each small box, there are 2x balls in each big box. And there are four boxes in size, so the equation 4x+2x times 4=360, which means 12x=360, so x=30 2x=60.

So there are 30 balls in each small box and 60 balls in each big box.