First let's find the number of ways we can create the sets that contain 12
things each. Suppose the sets A, B, and C contain 12 things each
We can fill set A in C(50,12) waye, set B in C(38,12) ways and set C(26,12).
That's C(50,12)·C(38,12)·C(26,12) ways. However we do not want to count
separately any two cases say, Case 1 and Case 2, where in Case 1, set A is
identical with set C of Case 2, set B is identical with set A of case 2, and
set C is identical with set B of Case 2. So to eliminate those duplicate
cases we must divide by 3!
So the number of ways to create the 3 sets of 12 is
For each of those ways of creating the sets of 12, we can create the
2 sets of 7 using the same reasoning in
So the answer is


or
or about 9.8×1029
Edwin