conversations.from: human
conversations.value: Please show me the solution for: Linda makes and sells necklaces at craft fairs. At her most recent fair she sold 4 necklaces and 8 rings for a total of $80. If each necklace costs $12, how much does each ring cost?
conversations.from: assistant
conversations.value: Let’s use r for the cost of each necklace
  4*12+8*r=80
  48+8*r=80
  8*r=80-48=32
  8r=32
  r=4 dollars for each ring