Consumers' Surplus The demand function for a certain make of replacement cartridges for a water purifier is given by the following equation where p is the unit price in dollars and x is the quantity demanded each week, measured in units of a thousand. p = -0.01x2 -0.2x + 15 Determine the consumers' surplus if the market price is set at $7/cartridge. (Round your answer to two decimal places.) $ 93.33 x The units in the original equation are in thousands.