五、A good is traded in a perfectly competitive market. The demand function is given by $X = 75 - 5P$, where $X$ is the quantity demanded, and $P$ is the price.

1. Assume the supply is perfectly elastic at the price $P = 10$. Please calculate the tax revenue, and the tax incidence on the buyer and seller, respectively, if an ad valorem tax at a rate of $t = 0.2$ is introduced. (9分)