a.
WACC is calculated as –
WACC = (Weight of common stock X Cost of common stock) + (Weight of preferred stock X Cost of preferred stock) + (Weight of debt X After tax cost of debt)
WACC = (64% X 13.4%) + (9% X 6.4%) + (27% X ((1- 40%)*8.1%))
WACC = 10.46%
b. After tax cost of debt is calculated as –
After tax cost of debt = (1- tax rate) X cost of debt pre-tax
After tax cost of debt = ((1- 40%)*8.1%))
After tax cost of debt = 4.86%