Luke and Owen have $100 each. Their friend offered to invest their money, promising to return a sumr times as great as what they invested. Luke was suspicious, so he invested $10 only, but Owen invested his
entire $100. Fortunately, the friend did indeed return a sum r times as great to each.
They decided to make another investment. This time, Owen invested all of the money returned to him, and
Luke invested the money returned to him and the remaining $90. Again, they got a sum r times as great as
what they invested. In the end, Owen had $337.50 more than Luke.
Write an equation in terms of r that models the situation.