What is the formula for the above question;

Joe's Tire Company has two support$$ departments, Personnel and Maintenance. The Maintenance Department costs of$$ $$80,000$ are allocated on the basis of standard service hours used. The Personnel Department costs of$$ $$20,000$ are allocated based on the number of employees. Costs of Departments A and B are$$ $$40,000$ and$$ $$60,000,$ respectively. Data on standard service hours and number of employees are as follows. What is the cost of the Maintenance Department allocated to Department B using the step down method if the support department with the highest percentage of interdepartmental service to the other support department is allocated first