conversations.from: human
conversations.value: Carlos is planting a lemon tree. The tree will cost $90 to plant. Each year it will grow 7 lemons, which he can sell for $1.5 each. It costs $3 a year to water and feed the tree. How many years will it take before he starts earning money on the lemon tree?
  What is the solution?
conversations.from: assistant
conversations.value: He makes $10.5 selling lemons each year because 7 x 1.5 = 10.5
  He earns $7.5 each year from the lemon tree because 10.5 - 3 = 7.5
  It will take 12 years to earn enough to pay off the tree because 90 / 7.5 = 12
  He will make money in year 13 because 12 + 1 = 13