SOLUTION: How many mg of salt would you have to add to a 18mg solution of 20% to make it 35%

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Question 672460: How many mg of salt would you have to add to a 18mg solution of 20% to make it 35%
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = mg of salt to be added
+.2%2A18+=+3.6+ mg of salt already in solution
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+%28+x+%2B+3.6+%29+%2F+%28+18+%2B+x+%29+=+.35+
+x+%2B+3.6+=+.35%2A%28+18+%2B+x+%29+
+x+%2B+3.6+=+6.3+%2B+.35x+
+.65x+=+2.7+
+x+=+2.7+%2F+.65+
+x+=+4.154+
4.154 mg of salt should be added
check:
+%28+4.154+%2B+3.6+%29+%2F+%28+18+%2B+4.154+%29+=+.35+
+7.754+%2F+22.154+=+.35+
+7.754+=+.35%2A22.154+
+7.75+=+7.7539+
close enough