Statins are used to keep cholesterol in check and are a top-selling drug in the U.S. The equation: S-1.7x = 5 gives the amount of sales (S) of statin in billions of dollars a years after 1998. According to this equation, how much will/did people in the U.S. spend on statins in the year 2013? Answer: People in the U.S. will spend billion dollars on statins in 2013.