Jeff sells T-shirts at a single price, which is the same across all the designs. The total demand of all the T-shirt designs as a function of price p is: D(p)=1000-5p, and the cost of producing each T-shirt is $20 dollar. What is the optimal price Jeff should charge to maximize his total profit? With this price, how much money Jeff leaves on the table for his customers? Suppose Jeff is able to charge two separate prices, can you find a two-price menu to improve his profit?