SOLUTION: A metallurgist has one alloy cantaining 20% copper and another containing 70% copper. How many pounds of each alloy must he use to make 50 pounds of a third alloy containing 50% c

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Question 52688This question is from textbook Intoductory Algebra
: A metallurgist has one alloy cantaining 20% copper and another containing 70% copper. How many pounds of each alloy must he use to make 50 pounds of a third alloy containing 50% copper?
Find the equation(s) and solve. This question is from textbook Intoductory Algebra

Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
Let the amount of 20% copper=x
Then the rest of the mixture would be 70%, let the amount of 70% mixture=50-x
You multiply percent times amount to get the solutions.
.20x+.70(50-x)=.50(50) To eliminate the decimals, multiply both sides of the equation by 100 or 10.
10(.20x)+10(.70)(50-x)=10(.50)(50)
2x+7(50-x)=5(50)
2x+350-7x=250
-5x+350=250
-5x+350-350=250-350
-5x=-100
-5x/-5=-100/-5
x=20
The amount of 20% alloy is 20 pounds.
The amount of 70% alloy is 50-20=30 pounds.