Some of 45%-intensity red paint is replaced with 25% solution of red paint such that the new paint intensity is 40%. What fraction of the original paint was replaced? Pick one: A) 2/5 B) 1/4 C) 1/5 D) 1/7 E) 2/3
Let total paint = 1   Let amount replaced = x   45 (1-x) + 25x = 40   x = 1/4   ANSWER:1/4
<result>B</result>
Some of 45%-intensity red paint is replaced with 25% solution of red paint such that the new paint intensity is 40%. What fraction of the original paint was replaced?