What is the implied APR the manufacturer would be charging you on the lease contract?

Problem: - Your firm is purchasing a new telephone system that will last for four years. - You can purchase the system for an upfront cost of $150,000, or you can lease the system from the manufacturer for $4,000 paid at the end of each month. - The lease price is offered for a 48-month lease with no early termination-you cannot end the lease early. - Your firm can borrow at an interest rate of 6% APR with monthly compounding. - Should you purchase the system outright or pay $4,000 per month