why does the solution say that N needs to be multiplied by 2? how did they come to that conclusion?

Rogers has 48 million shares of common stock outstanding. The book value per share is $42 but the stock sells for $58. It also has 1,000,000, 9 percent semiannual coupon bonds outstanding, par value $1,000 each. The bonds have 10 years to maturity and sell for 86 percent of par. Rogers common stock is half as risky as the market portfolio and held by the general public. Rogers has 10 million shares of 5 percent preferred stock outstanding which currently sell for $63 per share which are entirely owned by the Rogers family. The face value per preferred share is $100. The T-bills yield 5.25%, and the market risk premium is assumed to be 4.15%. Rogers is in the 35% corporate income tax bracket. Rogers's after-tax cost of debt is: 4.53% 6.45% 6.96% 7.40% 11 54% EDP-9579'.\" FV= 1000 PV = 0.86 *1000 = - 860 N =10 *2 = 20 PMT = 1000 * 0.09/2 = 45 Calculate IIY = 5.69 Before tax cost of debt = 5.69 * 2 = 11.38 Bfter Tax Cost of debt = 11.38 * ( 1 0.35) = 7.397 - 7.4% Answer D