Çözüldü Combination and Counting by Multiplication - Factorial

https://i.ibb.co/990JyvF9/kombinasyon.png
https://perfectmathsat.com/hard-act-questions/
(Question 1)

C(7, 2)·C(3, 1) = { 7! / [ 2!·(7 - 2)! ] }·{ 3! / [ 1!·(3 - 1)! ] } =
[ 5!·6·7 / (2·5!) ]·[ 2!·3 / (1·2!) ] = 21·3 = 63.