City of Auburn has a contract with a small company for parking and maintenance of police cars. The company charges the city $ 1.100 per car per year. City plans to buy a small parking space and terminate the contract. The parking space would cost $ 150.000 to buy and the operational cost is $ 60.000 per year. Also, there is additional parking cost of $ 500 per car, per year. Assuming the parking space will be used for 20 years with a salvage value of $ 50.000 after that, find the minimum number of cars that would make buying such a parking space viable for the city. Use 6% per year interest rate.