The Molding Department of Kennett Company has the following production data: beginning work in process $25,000$ units $(60\%$ complete$),$ started into production $475,000$ units, completed and transferred out $450,000$ units, and ending work in process $50,000$ units $(40\%$ complete$).$ Assuming materials are entered at the beginning of the process, equivalent units for materials are:

a$.500,000.$

b$.425,000.$

c$.450,000.$

d$.525,000.$