Answer: 13%
Explanation:
By substituting 20% of debt for debt yielding 8%, the company now has 20% financing from debt and 80% from equity.
The expected return on common stock after refinancing can be calculated by;
Return after refinancing = Return before refinancing + [tex]\frac{Debt}{Equity}[/tex](return before refinancing - Debt yield)
= 12% + [tex]\frac{0.2}{0.8} (0.12 - 0.08)[/tex]
= 13%