SOLUTION: Please help me solve this word problem: How many liters of water must be added to 20 L of an 85% solution of ammonia that is 70% ammonia?

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Question 698523: Please help me solve this word problem: How many liters of water must be added to 20 L of an 85% solution of ammonia that is 70% ammonia?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = liters of water to be added
+.85%2A20+=+17+ liters of ammonia in 85% solution
The key is that you have the same liters of ammonia
at the end as you started with.
+17+%2F+%28+20+%2B+x+%29+=+.7+
+17+=+.7%2A%28+20+%2B+x+%29+
+17+=+14+%2B+.7x+
+.7x+=+3+
+x+=+4.286+
4.286 liters of water need to be added
check:
+17+%2F+%28+20+%2B+4.286+%29+=+.7+
+17+%2F+24.286+=+.7+
+17+=+.7%2A24.286+
+17+=+17+
OK