Write a system of equations to describe the situation below, solve using substitution, and fill in the blanks.
A video rental company offers a plan that includes a membership fee of $7 and charges $2 for every DVD borrowed. They also offer a second plan, that costs $19 per month for unlimited DVD rentals. If a customer borrows enough DVDs in a month, the two plans cost the same amount. What is that total cost of either plan? How many DVDs is that?
