Raj is studying art at the local community college. He wants to take a stained glass art class that will count as 4 credits toward his degree. The college charges d dollars for each credit and a one-time fee of $150.00 for supplies. Raj determines that $540.60 will be the total cost of the class. Write an equation he can use to find d, the amount the college charges per credit.

How much does the college charge per credit?