5th grade math
posted by lost .
Larsen's class collected 137 cans. Schmidt's class collected 87 cans & Lopez's class collected 197 cans. Use mental math to see how many more cans Lopez's class collected than Schmidt's. (Got answer of 110) How many more cans did Larsen's class collect than Schmidt's. (Got answer of 50) Which property did you use to help you subtract mentally? Explain how you used it. Don't know how to answer the last 2 questions.

How did you do it?
http://www.google.com/search?client=safari&rls=en&q=math+property&ie=UTF8&oe=UTF8 
maximum help

50