SOLUTION: how many kilograms of salt must be added to 35kg of a 15% salt solution to make a 25% salt solution?

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Question 541397: how many kilograms of salt must be added to 35kg of a 15% salt solution to make a 25% salt solution?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = kg of salt needed
given:
+.15%2A35+=+5.25+ kg of salt in 15% solution
In words:
( total kg of salt ) / ( total kg of solution ) = 25%
+%285.25+%2B+x%29+%2F+%2835+%2B+x%29+=+.25+
+5.25+%2B+x+=+.25%2A%28+35+%2B+x+%29+
+5.25+%2B+x+=+8.75+%2B+.25x+
+.75x+=+8.75+-+5.25+
+.75x+=+3.5+
+x+=+3.5+%2F+.75+
+x+=+4.667+
4.667 kg of salt must be added
check:
+%285.25+%2B+x%29+%2F+%2835+%2B+x%29+=+.25+
+%285.25+%2B+4.667%29+%2F+%2835+%2B+4.667%29+=+.25+
+9.917+%2F+39.667+=+.25+
+9.917+=+.25%2A39.667+
+9.917+=+9.9167+
looks OK