You have a deck of 60 cards: 15 Red, 45 Blue. You draw 6 cards. What are the odds that you draw 2 Red?
To get red-red-blue-blue-blue-blue would be 15/60 x 14/59 x 45/58 x 44/57 x 43/56 x 42/55.
But this is not the only arrangement; there are actually 15 ways to end with two reds and four blues, so take the above answer times 15.