Cranston Company Estimates the Following Overhead Costs for the Coming

Cranston Company estimates the following overhead costs for the coming year: $$\begin{array} { l c } \text { Equipment depreciation } & \$ 160,000 \\\text { Equipment maintenance } & 60,000 \\\text { Supervisory salaries } & 40,000 \\\text { Factory rent } & \underline { 100,000 } \\\text { Total } & \$ 360,000 \\\hline\end{array}$$ Cranston is also budgeting $600,000 in direct labor costs and 15,000 machine hours for the coming year.
Required:
a. Calculate the predetermined overhead rate using direct labor costs as the allocation base.
b. Calculate the predetermined overhead rate using machine hours as the allocation base.