A large real estate office wants to rent a new copying machine. One desktop model will cost Rs. 200 per month for rental and Re 0.035 per copy. Another large model will cost Rs 400 per month for rental and Re 0.02 per copy. Currently, the office makes about 15000 copies per month. Which machine should they rent? What is the smallest number of copies per month that would make it desirable to rent the larger model?