SOLUTION: A metal worker has a metal alloy that is 30% copper and another alloy that is 70% copper how many kilograms of each Alloway should the metalwork are combined to create 90 KG of a

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Question 1007013: A metal worker has a metal alloy that is 30% copper and another alloy that is 70% copper how many kilograms of each Alloway should the metalwork are combined to create 90 KG of a 62% copper alloy
Found 2 solutions by fractalier, josgarithmetic:
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the amount of 30% alloy.
Then 90-x will be the amount of 70% alloy.
The set up looks like this then...
.30x + .70(90-x) = .62(90)
.30x + 63 - .70x = 55.8
-.40x = -7.2
x = 18 kg at 30% and so
90-x = 72 kg at 70%

Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
system%28%2830x%2B70y%29%2F90=62%2Cx%2By=90%29

simpler,
system%28%283x%2B7y%29%2F9=62%2Cx%2By=90%29
Not tricky. Linear system.

You could also choose to do in just one single variable as demonstrated here:
just one variable to solve two-part percent mixture