A firm is planning a business expansion and currently has a capital structure consisting of common stock of 5 million (200,000 shares)  in debt of 10 million with a 4% coupon rate. The firm has two different financing plans they need to decide between.
1)  sell an additional 80,000 shares for a total of $2 million.
2)  sell an additional 2 million of debt with a 5% coupon rate

What level of operation income would make the firm in different to either plan? Assume a 21% tax rate.