conversations.from: human
conversations.value: Explain how to solve this math problem: Lidia bought a new tablet, and she needs to buy some apps for it. One app costs $4 on average, and Lidia needs 15 of them. She has $66 for this purpose. How much money will she be left with if she buys all the apps she needs?
conversations.from: assistant
conversations.value: So Lidia will spend 4 * 15 = $60 on apps.
  She already has $66, so she will be left with 66 - 60 = $6.