The company cost of capital for a firm with a 65/35 debt/equity split, 8% after-tax cost of debt, 15% cost of equity, and a 35% tax rate would be:

a) 9.12%

b) 7.02%

c) 10.45%

d) 13.80%

Every time I solve this, I get 8.63%. What am I doing wrong?