<PRE><B>Question 469583</B>
An artist has 30kg of an alloy that is 45% copper. How many kilograms of a second alloy that is 70% copper should be mixed with the first alloy to get a new alloy that is 60% copper
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Equation:
copper + copper = copper
0.45*30 + 0.70x  = 0.60(x + 30)
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Multiply thru by 100 to get:
45*30 + 70x = 60x + 60*30
15*30 = 10x
x = 5 kg (amt of 70% alloy needed)
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Cheers,
Stan H.
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