Implicit rate on finacial Lease

Pg. 455 of Vol3, Financial analysis states to calculate the implicit rate of return for a lease, you set CF_Zero to the present value of the future min lease payments, $13,581, then solve for IRR. What is the source of the $13,581? This is a given number. in Practice, would it the the actual Sales price of the asset being Financed?

you should be using your financial calculator for this one, i cant remember the exact calc but something like I/R=? FV=0 Payment=? CMPT PV