SOLUTION: how many quarts of pure antifreeze must be added to 2 quarts of a 10% antifreeze solution to obtain a 50% solution?

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Question 643971: how many quarts of pure antifreeze must be added to 2 quarts of a 10% antifreeze solution to obtain a 50% solution?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = quarts of pure antifreeze needed
+.1%2A2+=+.2+ quarts of pure antifreeze in 10% solution
+%28+x+%2B+.2+%29+%2F+%28+x+%2B+2+%29+=+.5+
+x+%2B+.2+=+.5%2A%28+x+%2B+2+%29+
+x+%2B+.2+=+.5x+%2B+1+
+.5x+=+.8+
+x+=+1.6+
1.6 quarts of pure antifreeze must be added
check:
+%28+1.6+%2B+.2+%29+%2F+%28+1.6+%2B+2+%29+=+.5+
+1.8+%2F+3.6+=+.5+
+1.8+=+.5%2A3.6+
+1.8+=+1.8+
OK