SOLUTION: how many liters each of 15% acid solution and 33% acid solution should be mixed to get 120 L of 21% acid solution? what i have so far. liter of sol. percent lit

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Question 412299: how many liters each of 15% acid solution and 33% acid solution should be mixed to get 120 L of 21% acid solution?
what i have so far.
liter of sol. percent liter of acid
x 15% .15 .15x
y 33% .33 .33y
120 21% .21 .21(120)

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
how many liters each of 15% acid solution and 33% acid solution should be mixed to get 120 L of 21% acid solution?
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Equation:
acid + acid = acid
0.15x + 0.33(120-x) = 0.21*120
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Multiply thru by 100 to get:
15x + 33*120 - 33x = 21*120
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-18x = -12*120
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x = (2/3)*120
x = 80L (amt of 15% solution needed)
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120-x = 40L (amt. of 33% solution needed)
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Cheers,
Stan H.