SOLUTION: a certain alloy contains 9% silver , another alloy is 14% silver. HOW MUCH OF EACH TYPE SHOULD BE COMBINED TO MAKE 10 KG OF AN ALLOY THAT CONTAINS 12% SILVER?

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Question 715739: a certain alloy contains 9% silver , another alloy is 14% silver. HOW MUCH OF EACH TYPE SHOULD BE COMBINED TO MAKE 10 KG OF AN ALLOY THAT CONTAINS 12% SILVER?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Amount of Silver divided by amount of alloy equals 12%.

x the 9% Silver. y the 14% Silver.
%289x%2B14y%29%2F10=12 and x%2By=10.

Use the rational percent equation first.
9x+14y=120

The system to solve is this:
highlight%289x%2B14y=120%29
highlight%28x%2By=10%29
Try elimination. Multiply second equation by 9 and subtract from first equation. Solve for value of y.
9x+14y-9x-9y=120-90
5y=30
highlight%28y=6%29 kg of the 14% alloy

Use the second equation, the mass equation, to get the value for x.
highlight%28x=4%29 kg of the 9% alloy