Pack-Em-In Real Estate is building a new housing development. The more houses it builds, the less people will be willing to pay, due to the crowding and smaller lot sizes. In fact, if it builds 20 houses in this particular development, it can sell them for $640,000 each, but if it builds 60 houses, it will only be able to get $480,000 each. Obtain a linear demand equation. HINT [See Example 3.] (Let p be the price of a house and q the number of houses.)

Question:

p(q)=