Alyeska Services Company, a division of a major oil company, provides various services to the operators of the North Slope oil field in Alaska. Data concerning the most recent year appear below: Sales $ 7,500,000 Net operating income $ 600,000 Average operating assets $ 5,000,000 Required: 1. Compute the margin. 2. Compute the turnover. (Round your answer to 1 decimal place.) 3. Compute the return on investment (ROI). (Do n