$1.$ Humphrey Chimpden Earwicker, a recent immigrant from Dublin, is creating a pro forma for the development of a mixed$-$use four$-$stay building at Main and Hasting; in Vancouver, which is scheduled to be finished on $31$ December $2023.$ he has already leased the first floor to a pub, the second to a small law firm and the third to a startup software company. Owing to the unfortunate use of soluble roofing tiles by a subcontractor, the fourth floor is vacant and expected to remain so indefinitely. The leases specify the occupied space and monthly rent, both per square foot, and that tenants pay monthly operating cats of $$6\mathrm{.}00$ per square foot for the space they occupy. Humphrey is liable for the operating costs for the vacant fourth floor. Humphrey is also responsible for paying all property tax, which on a monthly basis is $$4\mathrm{.}50$ per square foot. Based on these figures, compiled in the table below, what does Harvey calculate for monthly NOI from his completed project?$\text{'}$