Mr. lewis is going on a trip. he has 11 books that he hasn't read yet, but he wants to bring only 2 on the trip. in how many ways can he choose 2 books to bring on the trip?

In this problem, we will use the combination formula. Combination is where the order of the things doesn’t matter.

So the formula for this problem is:

n! divided by r! (n-r)! = n/r

where:

n is the number of things to choose from and we choose r of them

11C2 = 11! / [2! (11 - 2)!] 
= 11! / (2! * 9!) 
= 55

step-by-step explanation:

y=mx+b