You build a four story 50,000 sqft GFA office building with 85% efficiency (rentable area/GFA) with 1 story of underground parking with 35 stalls, and with 120 surface stalls. Hard cost is $125 SF/GFA for the office, hard cost for underground parking is $15,000/space and surface parking cost is $1,000/space. Soft cost is 15% of hard cost (office+parking) including construction interest. The cost to acquire the land is $1,735,919. You have a loan at 70% LTC at an 8% mortgage constant, with the balance of funds from your equity investors. The triple net rent for the office space is $22/sqft, your occupancy is expected to be 92%, and the tenant expense pass-through is grossed up to 100% occupancy (100% of the expenses are paid by tenants regardless of occupancy, so NNN rent collected equals NOI). What is the maximum your equity investors can demand for cash on cash return expressed as a percentage to make this project feasible?