I am working on Chapter 30, Problem 13SQ (Valuing a Lease Renewal Option) in the textbook Commercial Real Estate Analysis and Investments (with CD-ROM) (2nd Edition) as shown below:

(Valuing a Lease Renewal Option) Use the methodology described in Appendix 30A for this chapter contained on the text CD to quantify the impact on the effective rent of the lease in Problem 30.12(a), if the lease also includes a renewal option for the tenant, giving the tenant the right (but not obligation) to renew the lease after five years at $16/SF. Assume that the present subjective probability regarding the market effective rents for new five-year leases, five years from now, is that there is a 50% chance that the market rent will be $18/SF, and a 50% chance that it will be $14/SF. Discount existing lease cash flows at 10% for the purpose of determining effective rent or existing lease present value, and future option values at 20% per year for the purpose of determining risk-adjusted present value.

I found the solution online (see below) but do not understand the answer for Step One,solving for the present value of a 5-year net lease at the rate of $15/SF and provision of 1-year free rent. The solution provided online is LPV= $47.54798. I created an Excel spreadsheet and keep getting: LPV= $45,589 or NERR of $11.45.