Don't mind the work below number 14 but i can't figure #14 out?

Due to bad planning, two of the local schools have their annual plays on the same weekend. while 457 people attend one, and 372 attend the other, only 104 people were able to attend both. how many people went to at least one play?

I’m really confused and need to learn this

Find the values of the variables and the lengths of the sides of this kite.