SOLUTION: A chemist wants to make a 10% solution of fertilizer. How much water and how much of a 30% solution should the chemist mix to get 30L of a 10% solution?

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Question 704475: A chemist wants to make a 10% solution of fertilizer. How much water and how much of a 30% solution should the chemist mix to get 30L of a 10% solution?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Question is typical, typical, typical! Rational expression equals a value.

Let x be how much water, y is how much of the 30%.
y%2A0.30%2F%28w%2By%29=0.10
x%2By=30

Solve one of the equations for x and substitute into the other equation and solve for y. Now use either equation to solve for x value.

You'll see that I did not put any "x" into the numerator of the rational equation. Do you understand why? ( x*0=0, the water by itself has no fertilizer ).

Since you know 30 liters is the amount of mixture desired, the rational equation can be written, y%2A0.30%2F30=0.10, and in this case is simpler.