How to Solve Venn Diagram Problems

Venn Diagram has been one of the mystifying ways of solving problems in mathematics. These are used specially when it comes to survey problems. The video below vividly and simply explains how these kind of problems are solved. Here the creator used the process of solving backwards. Let us solve Venn Diagram problems easily.
The first sample problem looks like this:

Here is the full video.

Hope this helped out.
@NicoCalunia