Equality of the classes

Here's another little mathematical problem to give to upper primary school children. As with the previous problem, the actual calculations are simple. The challenge is working out what to do with all the information given here.

There are 60 children in a school, in two classes, A and B. The school moves 5 children from Class A to Class B. Then 3 children are moved from Class B to Class A. They then decide to make a new class, Class C. So, 12 children from Class A and some children from Class B are moved to Class C, so that there is now the same number of children in each of the three classes. How many children were there in Class A and Class B to begin with?

Solution to follow.