conversations.from: human
conversations.value: Please show me the solution for: Violetta wants to buy new crayons. She needs them in 5 different colors and prepared $20 for this purchase. One crayon costs $2. How much change will she get?
conversations.from: assistant
conversations.value: Violetta is going to pay 5 * 2 = $10 for the crayons she wants.
  If she pays $20, she will get 20 - 10 = $10 of change.