Lincoln had 2 books in his backpack. one book had a mass of 3 pounds 7 ounces, and the other book had a mass of 2 pounds 10 ounces. what was the total mass in ounces of the books?

Lincoln will have 97 ounces in his backpack, to figure this out you add 3+2 and get 5 then you multiply that by 16 because there are 16 ounces in pound then you add 10 ounces and 7 ounces and end up with an answer of 80.