Water heater math problem

Question

 A solar water heater costs about $6240 to install (after rebates). A traditional gas water heater costs about $850, and costs about $320 per year to run. The average annual cost to run the solar water heater is about $75. A) Create total cost functions for each of the water heaters as a function of the number of years that it is used, and graph these functions on the same set of axes.

Answer 1

Let "y" represent the number of years you run the water heater and let "c" be the total cost

Solar:

c = 6240 + 75y

Traditional Gas

c = 850 + 320y

The graphs will look something like this: