I am particularly lost on what calculations I need to use in order to graph this problem in excel. thank you in advance

Leverage and the cost of capital

Leverage and the cost of capital Hubbard's Pet Foods is financed 80% by common stock and 20% by bonds. The expected return on the common stock is 12% and the rate of interest on the bonds is 6%. Assuming that the bonds are default-risk-free, draw a graph that shows the expected return of Hubbard's common stock (rE) and the expected return on the package of common stock and bonds (rA) for different debt-equity ratios.