Carla's team won 3 of its 5 games. Elena's team won games at the same rate and won 12 games. How many games did Elena's team play?

This is all about proportions. You can make this into fractions:

3/5 = 12/x

A good way to handle this, is to make one of those numbers the same. If you do (3/5) * 4, you would get 12/20 (because 4 * 3 = 12 and 4 * 5 = 20)

So then you have this:

12/20 = 12/x

It's basically a fill in the blank from there. x = 20

Elena's team played 20 games