SOLUTION: How much pure acid should be mixed with 2 gallons of a 60% acid solution in order to get a 90% acid​ solution?

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Question 1046721:
How much pure acid should be mixed with 2 gallons of a 60% acid solution in order to get a 90% acid​ solution?

Found 2 solutions by addingup, josmiceli:
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
x+0.6(2) = 0.9(x+2)
x+1.2 = 0.9x+1.8
0.1x = 0.6
x = 6 gallons
You need 6 gallons of pure acid added to your 2 gallons at 60% in order to get 8 gallons of a 90% solution

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = gallons of pure acid needed
+.6%2A2+=+1.2+ = gallons of pure acid in 60% solution
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+%28+x+%2B+1.2+%29+%2F+%28+x+%2B+2+%29+=+.9+
+x+%2B+1.2+=+.9%2A%28+x+%2B+2+%29+
+x+%2B+1.2+=+.9x+%2B+1.8+
+.1x+=+.6+
+x+=+6+
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6 gallons of pure acid are needed
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check:
+%28+x+%2B+1.2+%29+%2F+%28+x+%2B+2+%29+=+.9+
+%28+6+%2B+1.2+%29+%2F+%28+6+%2B+2+%29+=+.9+
+7.2+%2F+8+=+.9+
+7.2+=+.9%2A8+
+7.2+=+7.2+
OK