SOLUTION: How many lb of copper which costs $2/lb must be added to 3 lb of tin which costs $8/lb to make bronze which costs $4/lb?

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Question 1044953: How many lb of copper which costs $2/lb must be added to 3 lb of tin which costs $8/lb to make bronze which costs $4/lb?
Answer by ikleyn(52788) About Me  (Show Source):
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How many lb of copper which costs $2/lb must be added to 3 lb of tin which costs $8/lb to make bronze which costs $4/lb?
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Let x be the amount of copper and y be an amount of tin.

Then the price of the bronze will be

%282x+%2B+8%2A3%29%2F%28x+%2B+3%29.

Since it should be $4/lb, it gives you an equation

%282x+%2B+24%29%2F%28x+%2B+3%29 = 4.   (1)

It is an equation to solve for x.

So, multiply the equation by (x+3) to rid of the denominator. You will get

2x + 24 = 4x + 12,  or

2x = 24 - 12,  or

2x = 12,  or

x = 12%2F2 = 6.

So, you need to mix 6 lbs of copper to get your alloy.

For other solved problem on mixtures see the lessons
    - Mixture problems
    - More Mixture problems
    - Solving typical word problems on mixtures for solutions
    - Word problems on mixtures for antifreeze solutions
    - Word problems on mixtures for dry substances like coffee beans, nuts, cashew and peanuts
    - Word problems on mixtures for dry substances like candies, dried fruits
    - Word problems on mixtures for dry substances like soil and sand
    - Word problems on mixtures for alloys
    - Typical word problems on mixtures from the archive
in this site.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.