Please explain step by step. Thank you!

Kahle Company has two support departments: Purchasing and Payroll. The Purchasing Department expense is $500,000 to process 50,000 purchase requisitions, which are the cost driver for the department. The Payroll Department expense is $300,000 to process 25,000 payroll checks, which are the cost driver for the department. The Assembly Department has 50 employees and required the issuance of 1,300 payroll checks for the year. How much of the Payroll Department's cost is allocated to the Assembly Department?

a.$13,000

b.$20,800

c.$1,300

d.$15,600