Rumolt Motors has 16 million shares outstanding with a price of $25 per share. In addition, Rumolt has issued bonds with a total current market value of $483 million. Suppose Rumolt's equity cost of capital is 12%, and its debt cost of capital is 8%.

a. What is Rumolt's pretax weighted average cost of capital?

b. If Rumolt's corporate tax rate is 38%, what is its after-tax weighted average cost of capital?