The quantity demanded x of a certain brand of the DVD player is 3000/week when the unit price p is $485. The quantity demanded increases by 250 units for each decrease in unit price of $20 below $485. The suppliers will not market any DVD players if the unit price is $300 or lower. But at a unit price of $525, they are willing to make available 2500 units in the market. The supply equation is also known to be linear.