Pack-Em-In has another development in the works. If it builds 40 houses in this development, it will be able to sell them at $240,000 each, but if it builds 90 houses, it will get only $190,000 each. Obtain a linear demand equation. (Let p be the price of a house and q the number of houses.) Determine how many houses it should build to get the largest revenue? What is the largest possible revenue?