Given the following schedules, which is firm's optimal capital structure where the cost of capital is lowest? debt/assets cost of cost of debt equity 0% 7% 7 R 14% 14 14 14 16 8 18 which is firm's optimal capital structure? What is the weighted average cost of capital at optimal capital structure? debt/asset = 20%, WACC=12.20 debt/asset = 30%, WACC=12.20 debt/asset = 30%, WACC=12.60 debt/asset = 20%, WACC=12.60