Sentry Manufacturing just paid a dividend $5 per share. The dividend is expected to grow at a constant rate of 8% per year. The price of Sentry Manufacturing's stock today is $32 per share. If Sentry Manufacturing decides to issue new common stock, flotation costs will equal $2.70 per share. Sentry Manufacturing's marginal tax rate is 35%. Based on the above information, the cost of retained earnings (internal equity) is...?