A portion of the 85% solution of chemicals was replaced with an equal amount of 20% solution of chemicals. As a result, 40% solution of chemicals resulted. What part of the original solution was replaced? Answers:
A) 5/13 B) 6/13 C) 9/13 D) 13/9 E) 13/6
Let the original amount of 85 percent solution = x and amount replaced be y   0.85(x - y)+ 0.2y = 0.4 x   0.85x -0.85y+0.2y = 0.4x   0.45x = 0.65y   9x = 13y   y = 9x/13   So, amount replaced = 9/13 of original amount   ANSWER:9/13
<result>C</result>
A portion of the 85% solution of chemicals was replaced with an equal amount of 20% solution of chemicals. As a result, 40% solution of chemicals resulted. What part of the original solution was replaced?