Anna and Hannah have $\$80$ each. Their friend offered to invest their money, promising to return a sum $r$ times as great as what they invested. Anna was suspicious, so she invested $\$20$ only, but Hannah invested her entire $\$80$. Fortunately, the friend did indeed return a sum $r$ times as great to each. They decided to make another investment. This time, Hannah invested all of the money returned to her, and Anna invested the money returned to her *and* the remaining $\$60$. Again, they got a sum $r$ times as great as what they invested. In the end, Hannah had twice the amount Anna had. **Write an equation in terms of $r$ that models the situation.** [[☃ expression 1]]