Arithmetic Progress Quiz #2 Q8 (I'm Overwhelmed)

Question 8 asks you to multiple select the factors of 15! When reviewing the solution, I don’t quite understand what is happening here:

Specifically, the formula/equation that is used to determine the number of multiples. My quant foundation is not strong, so sorry if this is an obvious solution I’m not grasping.

What part do you not get? Do you understand that if 49 must divide 15!, 15! must contain all the prime factors present in 49?