A portion of the 90% 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?
Select the correct option:
A) 5/7	B) 6/7	C) 9/5	D) 13/9	E) 13/6
This is a weighted average question. Say x% of the solution was replaced --&gt; equate the amount of chemicals: 0.90(1-x)+0.2*x=0.4 --&gt; x=5/7.   5/7nswer: 5/7.
<result>A</result>
A portion of the 90% 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?