Is a monopoly still subject the laws of supply and demand?  How can it use these laws to its advantage?

If demand curve for monopoly is Q = 75 – P/2 and average variable cost is 50 and fixed cost is 25, what is the profit maximizing output and price?

Consider the local telephone company, a natural monopoly. The following graph shows the demand curve for phone services, the company's marginal revenue curve (labeled MR), its marginal cost curve (labeled MC), and its average total cost curve (labeled AC). (Hint: Click a point on the graph to see its exact coordinates.) PRICE (Dollars per month) 160 140 120 100 80 60 40 20 0 0 1 MR 2 3 4 567 QUANTITY (Thousands of households per month) AC MC D 8 (?)

What is the difference between a monopoly's marginal revenue curve and a perfect competitor's marginal revenue curve? Please explain the difference in these markets by drawing the graphs.