Ten firms compete in a market to sell product x. the total sales of all firms selling the product are $2,000,000. ranking the firms’ sales from highest to lowest, we find the top four firms’ sales to be $270,000, $215,000, $190,000, and $130,000, respectively. calculate the four-firm concentration ratio in the market for product x.

David paid $975,000 for two beachfront lots in coastal south carolina, with the intention of building residential homes on each. two years later, the south carolina legislature passed the beachfront management act, barring any further development of the coast, including david's lots. when david files a complaint to seek compensation for his property, south carolina refuses, pointing to a passage in david's own complaint that states "the beachfront management act [was] properly and validly designed to south carolina's " is south carolina required to compensate david under the takings clause?