Suppose we are given for identical red flags, 2 identical blue flags, and 3 identical green flags. Find the number of (M) different signals that can be formed by hanging the nine flags in a vertical line.

M=?

PLEASE DO NOT SOLVE! PLEASE only tell how to do the question.

2 answers

9! ways if all different

but the 4 red flags can be arranged in 4! ways, but they are identical.

Similarly for the other colors, so the distinguishable arrangements are

9!/(4!2!3!)
thanks!