The demand for video recorders has been estimated to be linear and given by the demand relation qv = 145 − 3.2pv + 7m − 0.95pf − 39 pm, where qv is the quantity of video recorders, pf denotes the price of video recorder film, pm is the price of attending a movie, pv is the price of video recorders, and m is income. based on the estimated demand equation we can conclude: