3. I have 4 identical math books, 3 identical English books, and 2 identical French books.
(b) In how many ways can I arrange all of them on a bookshelf and French books on the end?
+2401 /4/3/2 is because the 4 math books are the same.
So there 4*3*2 ways the arrange 4 seperate things, but since all of them are the same, we divide 4, 3, and 2.
Same with 3/2 because the 3 english books are the same.
I'm sorry, I'm not a teacher nor good at explaining.
If you're still confused, here's a video: https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:prob-comb/x9e81a4f98389efdf:combinations/v/introduction-to-combinations
=^._.^=
