This is a combination problem. The approach to this is by using the nCr method, where n is the number of total objects and r is the number of success. For example, if you want to get 3 red out of the total 4, then that would be 4C3. That means,
4C3 = 4!/3!(4 - 3)! = 4 ways
If you want to get 2 green out of the total 6, then that would be 6C2. That means,
6C2 = 6!/2!(6-2)! = 15 ways
Therefore, there are a total of 4+15 = 19 ways.
