7. The Black Hills Telephone Company, a utility serving rural customers in South Dakota is currently engaged in a rate case with the regulatory commission under whose jurisdiction it operates. At issue is the monthly rate the company will charge for call waiting service. The demand curve for this monthly service is P = $6.25 - $0.00025Q. This implies annual demand and marginal revenue curves of: P = $75 - $0.003Q MR = OTR/Q = $75 - $0.006Q where P is service price in dollars and Q is the number of customers served. Total and marginal costs per year (before investment return) are described by the function: TC = $108,000 + $25Q + $0.002Q MC = OTC/Q = $25 + $0.004Q The company has assets of $100,000 used for call waiting services and the utility commission has authorized a 12% return on investment. A. Calculate Black Hills' profit-maximizing price (monthly and annually), output, and rate- of-return levels. B. What monthly price should the commission grant to limit Black Hills to an 12% rate of return