conversations.from: human
conversations.value: I would love to understand how to solve this problem: Helena is a mad scientist testing her latest creation, the Lots-of-Limbs Serum. The serum will make the drinker grow an extra arm every three days and an extra leg every five days. After fifteen days, how many new limbs will Helena’s serum cause a person to grow if they drink it?
  Can you explain?
conversations.from: assistant
conversations.value: At one new arm every 3 days, after 15 days, a person who drank Helena’s serum would grow 15 / 3 = 5 extra arms.
  At one new leg every 5 days, after 15 days, the person would grow 15 / 5 = 3 extra legs.
  In all, someone who drank Helena’s serum would grow 5 + 3 = 8 new limbs after 15 days.