Vacation accrual formula

I need assistance, I do not know how to calculate vacation time for employees on a spreadsheet- We accrue weekly vacation-

40 hours after 1 year of service;
80 after 2 -15 years of service and
120 hours after 15th year.

I also want it to deduct when the employee takes time off automatically. We are based on a 52 week pay period. Any help?


This is greatly appreciated.