OKAY..
all you have to do is make a tree diagram. first on a paper write this down.

A= 1,2,3,4,5,6

B=1,2,3,4,5,6

B=1,2,3,4,5,6

C=1,2,3,4,5,6

C=1,2,3,4,5,6

C=1,2,3,4,5,6

So there are a total of 36 outcomes beacuse there are 36 possible numbers that could occur. Out of those the probability of(B,4) occuring is 2/36 or 1/18 (reduced answer) as shown above because there are 2 B'S and each has one 4 in it.