4. The Brown Company has estimated costs for the following monthly production levels: Production volume (units) 1000 2.000 3000 Cost A Cost B Cost C Cost D Cost E 20,000 $40,000 $60,000 6,000 9,000 12,000 18,000 18,000 18,000 11,000 16,000 21,000 15,000 15,000 15.000 $20.0:00 S98.000 126.000 Total manufacturing costs Required: a. Identify whether each cost would be a variable, fixed, or mixed cost b. Measure the following equation using the high-low method (hint: use the total manufacturing costs and units from the first and third columns.): Total manufacturing costs a+b(units)