SOLUTION: Please help, 36g of an alloy of copper and zinc contains 45% copper. How much pure copper do you need to add in order to get a 60% copper alloy?

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Question 941171: Please help,
36g of an alloy of copper and zinc contains 45% copper. How much pure copper do you need to add in order to get a 60% copper alloy?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
36g of an alloy of copper and zinc contains 45% copper.
How much pure copper do you need to add in order to get a 60% copper alloy?
:
let c = amt of pure copper required
:
write an equation using the decimal equiv of the per cent
c + .45(36) = .60(c + 36)
c + 16.2 = .60c + 21.6
c - .60c = 21.6 - 16.2
.40c = 5.4
c = 5.4/.4
c = 13.5 grams of pure copper required
:
:
You can confirm this for yourself, replace c with 13.5 in the original equation