The quantity demanded of a certain brand of DVD player is 3000/wk when the unit price is $485. For each decrease in unit price of $20 below $485, the quantity demanded increases by 250 units. The suppliers will not market any DVD players if the unit price is $283 or lower. But at a unit price of $508, they are willing to make available 2500 units in the market. The supply equation is also known to be linear.