Ineed you find 20 books that you checked out from the library as you are cleaning your room. you need to take 4 books back to the library, and you want to set them aside in a pile on your desk. â  how many ways can 4â  of the 20â  books be arranged in a pile?

There are 20 ways to pick the first book, 19 ways for the second

Step-by-step explanation:

If order of the 4 books does not matter then

₂₀C₄ = 20! / (20-4)!4! = 20!/(16!*4!) = 4845 ways

the answer is 5636.7

example 2 – simplify: step 1: completely factor both the numerators and denominators of all fractions. step 2: change the division sign to a multiplication sign and flip (or reciprocate) the fraction after the division sign; essential you need to multiply by the reciprocal. step 3 : cancel or reduce the fractions.