A monopolist operates in an industry where the demand curve is given byQ= 100 -P. The monopolist's constant marginal cost is $20.Using IEPR, derive the price elasticity of demand at the profit-maximizing price.

Assume that there is no fixed cost of production. Please draw the monopolists TC, TR, and profit functions. (Show the profit-maximizing condition of this monopolist, clearly indicating the profit-maximizing quantity and price.)