Each marble bag sold by Karen's Marble Company contains 3 blue marbles for every 5 yellow marbles. If a bag has 45 yellow marbles, how many blue marbles does it contain?

well you take 45 because thats your given amount of yellow. your given for every 5yellow they = 3 blue. so Divide 45 by 5 which give you 9. then you would multipy 9 by 3 to give you 27 blue marbles as your answer.