# Determine concentration

How would I go about solving a problem that goes roughly as such?

Solution A: .1%
Solution B: .15%


How many milliliters of each A & B are required to create 260 milliliters of a solution, C, that is .14%?

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Solve the following system:

1. $x+y = 260$
2. $0.1x+0.15y = (0.14)(260)$
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I keep getting a negative answer. I think I'm doing something wrong... Wouldn't I multiply the top by either -.1 or -.15? –  Josh Jan 13 '11 at 2:22
@Josh: The RHS of equation 2 should be 0.14*260. Then you should be OK. Can you explain why? –  Ross Millikan Jan 13 '11 at 2:38