SOLUTION: How many ounces of pure zinc must be alloyed with 20 ounces of brass that is 30% zinc and 70% copper to produce brass that is 40% zinc?

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: How many ounces of pure zinc must be alloyed with 20 ounces of brass that is 30% zinc and 70% copper to produce brass that is 40% zinc?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 826417: How many ounces of pure zinc must be alloyed with 20 ounces of brass that is 30% zinc and 70% copper to produce brass that is 40% zinc?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
One material quantity known, one material quantity unknown.
L = 30%
T = 40%, target value
H = 100%
U = 20 ounces
v = unknown, pure zinc, ounces

(Total zinc)/(total mixture amount)=(target concentration)

highlight%28%28LU%2BHv%29%2F%28v%2BU%29=T%29, solve for v.
LU%2BHv=Tv%2BTU
Hv=Tv%2BTU-LU
Hv-Tv=TU-LU
v%28H-T%29=TU-LU
highlight%28v=U%28T-L%29%2F%28H-T%29%29
'
Now you substitute the values to compute v.