Please help answer the question and show your work. thank you

You were hired as the CFO of a new company that was founded by three professors at your university. The company plans to manufacture and sell a new product, a cell phone that can be worn like a wrist watch. The issue now is how to finance the company, with equity only or with a mix of debt and equity. The price per phone will be $250.00 regardless of how the firm is financed. The expected fixed and variable operating costs, along with other data, are shown below. How mu Ch higher or lower will the firm's expected ROE be if it uses 60% debt rather than only equity, i.e., what is ROE_L - ROE_U? a. 15.70 % b. 13.65% c. 11.33% d. 12.56 % e. 16.52 %