<PRE><B>Question 1055347</B>
 How many kilograms of brass containing 63% copper must be melted with 1100 of brass containing 72% copper to produce a new brass containing 67% copper? 
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Equation:
cop + cop = cop
0.63x + 0.72*1100 = 0.67(x+1100)
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63x + 72*1100 = 67x + 67*1100
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4x = 5*1100
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x =  5*275
x = 1375 units (amt. of 63% brass needed)
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Cheers,
Stan H.
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