I can't seem to figure out b and c on this question.

Based on the best available econometric estimates, the market elasticity of demand for your firm's product is -2. The marginal cost of producing the product is constant at $75, while average total cost at current production levels is $140.

Determine your optimal per unit price if:

Instruction:Enter your responses rounded to two decimal places.

a. You are a monopolist.

$150

b. You compete against one other firm in a Cournot oligopoly.

c. You compete against 19 other firms in a Cournot oligopoly.