Answer:
The after-tax cost of debt for a new issue of bonds is 6.9%
Explanation:
After tax cost of debt = Before tax cost * (1-tax rate)
After tax cost of debt = yield to maturity * (1-tax rate)
After tax cost of debt = 10%*(1-0.31)
After tax cost of debt = 10%*0.69
After tax cost of debt = 6.9%