Current Attempt in Progress Let C(q) represent the cost, R(q) the revenue, and (q) the total profit, in dollars, of producing q items. (a) If C' (50) = 75 and R' (50) = 83, approximately how much profit is earned by the 51st item? The profit earned from the 51st item will be approximately $i (b) If C' (90) = 69 and R' (90) = 63, approximately how much profit is earned by the 91st item? The profit earned from the 91st item will be approximately $ (c) If (q) is a maximum when q = 78, how do you think C' (78) and R' (78) compare? C' (78) R' (78)