You have 10 houses in a row on a one side of a street, going from left to right. You are to paint three of them red, three of them white, and four of them blue. How many different color patterns can you come up with
The first choice can be any of the four colors. For each of these 4 first choices there are 3 second choices. Therefore there are 4 x 3 = 12 possibilitie