Roppongi Car Park is a small paid parking lot located in central Tokyo. Roppongi has fixed costs (rent of the land that it sits on) of ¥990,000 per month. They expect to charge ¥3,000 to park one car for one day. Assume that all customers park for the entire day. The lot has a capacity of 18 cars and only operates on weekdays (assume a total of 20 weekdays per month).

In addition, Roppongi hires a lot attendant who parks the cars and collects the cash. The attendant is paid 10% of revenues plus ¥150 per car parked.

Given the information above, what is Roppongi’s breakeven point (in number of cars parked per month)?