Question 386217
Lily mixed a 45% copper sulfate solution and a 25% copper sulfate solution to get 100 mL of a 31% copper sulfate solution. Haw many mL of the 25% solution did she use?
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Equations:
Quantity Eq::::  x + y = 100mL
Copper Eq::::: 0.25x+0.55y = 0.31*100
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Multiply Quantity by 55
Multiply Copper by 100
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55x  + 55y  =  55*100
25x  + 55y  =  31*100
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30x = 24*100
x = 80mL (amt. of 25% solution needed in the mix)
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Cheers,
Stan H.