conversations.from: human
conversations.value: Can you guide me through solving this problem: Ruel has four books of 10 stamps and six books of 15 stamps. How many stamps does Ruel have?
conversations.from: assistant
conversations.value: Ruel has a total of 4 x 10 = 40 stamps from the four books.
  He also has 6 x 15 = 90 stamps from the six books.
  Therefore, he has a total of 40 + 90 = 130 stamps.