Whats the after-tax cost of debt if the company has $50 million in 10 year debt that yields 6% and they are in the 21% tax bracket?

HelloDoggie uses common stock, preferred stock and debt to finance their business. They estimate the weight of common stock to be 55%, preferred stock to be 5% and debt to be 40%. The cost of common stock is 15%, the cost of preferred stock is 10% and the after-tax cost of debt is 8%. What is their weighted average cost of capital?