Isaiah is having his house painted. He paid $525 for the required materials, and he will pay $30 an hour for the painters to complete the job. Which equation shows the relationship between y, the number of hours the painters work, and x, the total cost of the project?
A. y = 525x + 30
B. y = 30x - 525
C. y= 30x + 525
D. y = 525x + 30