Need help with solving this problem in excel format. Thank you

ADVANCED PROBLEMS FOR SPREADSHEET APPLICATION 1. Changing WACC and optimal choice. Austin Enterprises is currently an all-equity firm. The firm is considering selling debt (bonds) and retiring some of the equity. However, at each level of debt, debt becomes more expensive (cost of debt is rising), and the riskiness of the equity also rises with more and more debt. Using a spreadsheet, determine the best combination of debt and equity for Austin Enterprises if The current beta of Austin Enterprises is 0.85. The current market return is 12%. The current risk-free rate is 3%. The total equity is 20,000,000 shares at $25 per share. Debt is sold in units of $2,000,000. The first unit of debt has a cost of 7.5%. The tax rate of Austin Enterprises is 40%. For each additional unit of debt (each additional $2,000,000), the cost of debt rises by 0.85%, and the beta of Austin Enterprises rises by 0.025. Where is the WACC the lowest? Graph the results of the changing WACC