please answer for b and c

Irving Corp. has no debt but can borrow at 6 percent. The firm's WACC is currently 11 percent, and there is no corporate tax. a. What is the company's cost of equity? (Do not round intermediate calculations and enter your answer as a percent rounded to the nearest whole number, e.g., 32.) b. If the firm converts to 15 percent debt, what will its cost of equity be? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) c. If the firm converts to 55 percent debt, what will its cost of equity be? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) d. What is the company's WACC in parts b) and c)? (Do not round intermediate calculations and enter your answers as a percent rounded to the nearest whole number, e.g., 32.) 11% % a. Cost of equity b. Cost of equity C. Cost of equity d. 15 percent debt 55 percent debt % 11% 11%