conversations.from: human
conversations.value: It takes Matt 2 minutes per problem to do his math homework with a calculator and 5 minutes per problem without a calculator. If Matt's assignment has 20 problems, how much time will using a calculator save?
  How to solve this?
conversations.from: assistant
conversations.value: First find the time difference per problem: 5 minutes/problem - 2 minutes/problem = 3 minutes/problem
  Then multiply that number by the number of problems to find the total time difference: 3 minutes/problem * 20 problems = 60 minutes