conversations.from: human
conversations.value: This math problem has got me stumped: Hawkeye is driving to his aunt. He has to charge his battery for $3.5 per charge. If he charged his battery four times, and his battery charging budget was $20, how much money was he left with when he reached his aunt's place?
  Can you show me the way?
conversations.from: assistant
conversations.value: If each battery charge costs $3.5, the total expense of 4 battery charges is 4*3.5 = $14.
  After his expense on battery charging, his balance was 20-14 = $6.