A store can sell 200 units of a certain brand of CD player when the unit price is set at $90. If the prices decreases by $50, the store will be able to sell 1200 units. When the unit price is $45, the wholesaler will provide 500 CD players, but if the price increases to $65, the wholesaler will provide an additional 200 units. Find the supply and demand functions (assume they are linear)