Ms. Stern’s class was having a party after school with popcorn. During the party, the class ate 1.72 pounds of popcorn. After the party, Ms, Stern weighed the popcorn and there was 1.82 pounds of popcorn in the bag. How many pounds of popcorn did Ms. Stern have before the party started?
the starting amount is what was left + what was eaten, right? So,
1.72 + 1.82 = ____