In how many ways it is possible to divide six identical green, six identical blue and six identical red among two persons such that each gets equal number of items?

THERE ARE TOTAL 18 BALLS(6 GREEN+6 BLUE+6 RED)

THESE BALLS SHOULD BE DISTRIBUTED EQUALLY AMONG TWO PERSONS SO THERE ARE AS MANY NUMBER OF WAYS AS IN WHICH WE CAN DIVIDE THESE BALLS IN TWO EQUAL GROUPS OF 9-9 BALLS.

SO THE REQUIRED ANSWER IS          18!/(9!*9!*2!).

HERE 2! IS BECAUSE TWO GROUPS HAVE SAME SIZE THAT IS 9