Tonya and Leo each bought a cell phone at the same time.

The trade-in values, in dollars, of the cell phones are modeled by the given functions, where x is the number of months that each person

has owned the phone.

Tonya's Phone

Leo's Phone

the trade-in value of

D phone has the greater initial trade-in value.

During the first four months, the trade-in value of Tonya's phone decreases at an average rate

Leo's phone.