i need the solution to this problem

7. Responsibility Accounting: a. What is a cost center? Give an example of a cost center b. What is a Profit center? Give an example of a profit center c. What is an investment center? Give an example of an investment center d. What is management by exception: e. The Hydride Division of Murdoch Corporation is an investment center. It has $1,000,000 of operating assets. During 2020, the Hydride Division earned operating income of $400,000 on $6,000,000 of sales. Murdoch's companywide return on investment or desired rate of return is approximately 15% SHOW WORK FOR CREDIT! 1. What is the ROI? 2. What is the margin? 3. What is the turnover? 4. What is the residual income