<PRE><B>Question 1072191</B>
A metal alloy is 35% copper.
 Another metal alloy is 50% copper. 
How much of each alloy should be used to make 600 grams of a metal alloy that is 45% copper? 
:
let x = amt of 50% alloy 
resulting amt is be 600 gr, therefore
(600-x) = amt of 35% alloy
:
Amt of copper equation
.50x + .35(600-x) = .45(600)
.50x + 210 - .35x = 270
.50x - .35x = 270 - 210
.15x = 60
x = 60/.15
x = 400 gr of 50% alloy required
then, obviously;
600-400 = 200 gr of 35% alloy
:
;
Check this in the original equation
.50(400) + .35(200) = .45(600)
200 + 70 = 270</PRE>