A firm's product sells for $4 per unit in a highly competitive market. The firm produces output using capital (which it rents at $25 per hour) and labor (which is paid a wage of $30 per hour under a contract for 20 hours of labor services). Complete the following table and use that information to answer the questions that follow. Instruction: Enter yout responses for Average Product of Capital (APK) and Average Product of Labor (APU) rounded to two decimal places. All other responses should be entered as whole numbers. If you are entering a negative number, use a negative sign (-) where appropriate. a. Identify the fixed and variable inputs. Copital is the fixed input and labor is the variable input. Capital and labor are variable inputs: Capital and labor are fixed inputs. Lobor is the fixed input and capital is the variable input. b. What are the firm's fixed costs? $ c. What is the variable cost of producing 475 units of output (use least-cost)? $ d. How many units of the variable input should be used to maximize profits? e. What are the maximum profits this firm can earn? $ f. Over what range of the variable input usage do increasing marginal returns exist? From to g. Over what range of the variable input usage do decreasing marginal returns exist? From to h. Over what range of input usage do negative marginal returns exist? From to