<PRE><B>Question 380090</B>
Determine the amount of a 25% acid solution and a 80% acid solution needed to make 250 mL of a 40% acid solution. 
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Equation:
acid + acid = acid
0.25x + 0.80(250-x) = 0.40*250
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Multiply thru by 100 to get:
25x + 80*250 - 80x = 40*250
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-55x = -40*250
x = 181.82mL (amt. of 25% solution needed in the mixture)
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250-181.82 = 68.18mL (amt. of 80% solution needed in the mixture)
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Cheers,
Stan H.</PRE>