Which of the following mathematical equations is used to calculate a predetermined overhead rate? a.Predetermined Overhead Rate = Actual Annual Cost of Goods Sold / Estimated Semi-annual Labor Hours b.Predetermined Overhead Rate = Actual Annual Overhead / Actual Annual Activity Level c.Predetermined Overhead Rate = Estimated Annual Manufacturing Cost / Estimated Quarterly Activity Level d.Predetermined Overhead Rate = Estimated Annual Overhead / Estimated Annual Activity Level e.Predetermined Overhead Rate = Estimated Annual Overhead / Actual Annual Activity Level