T-Galaxy Has Market Power in the Market for Iowa State $\iff$

T-Galaxy has market power in the market for Iowa State University Big XII Championship 2000 T-shirts. The demand for T-Galaxy's product is: Q_D = 10 - 0.4P $\iff$ P = 25 - 2.5Q_D. The resulting marginal revenue curve is MR(Q) = 25 - 5Q. T-Galaxy's marginal costs are MC(Q) = 3 + 6Q. Determine T-Galaxy's profit maximizing price. Calculate T-Galaxy's elasticity of demand at this price. What is T-Galaxy's mark-up over marginal cost as a percentage of price?