# How do I remove repetitions from a combinatorics problem?

Suppose there are 19 marbles in a bag: 5 red, 6 green, and 8 blue ones. How many ways can 5 marbles be selected if exactly 2 marbles are red and 3 are another color?

-
I'm not really sure what the title of the post is asking. If you want to choose $5$ marbles, $2$ of which are red and $3$ of which are not red, then there are no repetitions here. You need the Multiplication principle here (mathworld.wolfram.com/MultiplicationPrinciple.html). –  JavaMan Jan 18 '12 at 4:14
Maybe, it's also good to ask, whether OP is aware of the principle of inclusion-exclusion‌​? –  user21436 Jan 18 '12 at 4:17