The cost of renting a canoe to use on River Y costs ​$43. The cost of renting a canoe to use on River Z costs ​$4 per hour plus a ​$15 deposit. The total​ cost, c, of renting a canoe on either river for n hours can be represented by an equation. Write and graph a system to find how many hours you have to rent a canoe for the cost to be the same on both rivers.