The question says:in how many ways we could put 4 black,4 white,4 red balls in 6 different boxes?
boxes are distinguishable,black balls are identical,red balls are identical,and white balls are identical.
one or more box can remain empty.
i know number of ways to put k indistinguishable balls to n distinguishable boxes.but i don't know how to attack this problem because 3 different kind of balls.