Number of ways of selecting 2 fiction books = 5C2
Number of ways of selecting 2 non fiction books = 6C2
5C2 * 6C2 = 10 * 15 = 150
There are 5 fictions and 6 non-fictions. How many cases are there such that 2 fictions and 2 non-fictions are selected from them?
  * 90
  * 120
  * 150
  * 180
  * 200