our firm is purchasing a new telephone system, which will last for four years.There are two alternatives: purchase outright or lease. If the system is purchased, there is an upfront cost of 150K. If the system is leased from the manufacturer, then the firm must pay 4K at the end of each month for four years. Your firm can borrow from its local bank at an interest rate of 5% APR with semiannual compounding. With alternative is best?

Can someone explain how they figured out the monthly payment of 3,450.9 if take the loan and got a total cost of 173,867 for leasing. I'm not sure how to do it.