How many students take all three language classes?

[yoccooo]

I am working on Math homework, and I'm stuck...

Question:
There are total of 129 foreign language students in a high school where they offer Spanish, French, and German. You are given the following details:

53 take Spanish
54 take French
52 take German
34 students take at least 2 languages at once.

How many students take all three languages at once?

I appreciate any responses!

 

[Denis]

http://en.wikipedia.org/wiki/Venn_diagram