If after 400 grams of water were added to the 24%-solution of alcohol, the strength of the solution decreased by one-third, how much of the 24%-solution was used?  Select
A) 180 grams B) 220 grams C) 400 grams D) 800 grams E) 950 grams
The 24% alcohol solution decreases by 1/3 once the 400 grams of water is added so  400/.08= 
<gadget id="calculator"> 400/.08</gadget>
<output>5_000</output>
5000*.16% (2/3 of 24%) is 800 grams, thus answer is 800 grams.
<result>D</result>
If after 400 grams of water were added to the 24%-solution of alcohol, the strength of the solution decreased by one-third, how much of the 24%-solution was used?