2018 AMC 12A Problems/Problem 1
Problem
A large urn contains balls, of which are red and the rest are blue. How many of the blue balls must be removed so that the percentage of red balls in the urn will be ? (No red balls are to be removed.)
Solution
There are red balls; for these red balls to comprise of the urn, there must be only blue balls. Since there are currently blue balls, this means we must remove