Acommon equation used in business is a demand equation. it expresses the relationship between the unit price of some commodity and the quantity demanded. in the equation, p represents the unit price and x represents the quantity demanded in thousands. a company sells desk lamps and has found that the demand equation for a certain style of desk lamp is given by the equation p equals negative x squared plus 23. find the demand for the desk lamp if the price is $7 per lamp.