conversations.from: human
conversations.value: Heaven and her younger brother want to buy school supplies, so they ask their father for money, who gives them $100 in total to use. Heaven buys two sharpeners and four notebooks at $5 each, and her brother uses the remaining amount to buy ten erasers at $4 each and some highlighters. How much money did Heaven's brother spend on highlighters?
  Solve it.
conversations.from: assistant
conversations.value: Heaven spent 2*5=$10 on sharpeners.
  She also spent 4*5 = $20 on notebooks.
  Heaven's brother used 10*4 = $40 to buy erasers.
  The total amount of money Heaven and her sister spent on sharpeners, notebooks, and erasers is 40+20+10 = $70
  The total amount of money her brother spent on highlighters is 100-70 =$30