How to solve the problem with details please

20 1000 7. Assume that in the short run, a firm which is producing 100 units of output has average total costs of $200 and average variable costs of $150. The firm's average fixed costs are $50. If the price is $265 per unit at this level of production, assuming all 100 units produced are sold at this price, then marginal revenue is equal to: a. $115. b. $15,000. C./ $26,500. d. $6,500