<PRE><B>Question 202906</B>
If the price of copper is 65 cents/lb and the price of zinc is 30 cents/lb,
 how many pounds of copper and zinc should be mixed to make 70 lb of brass
 selling for 45 cents per pound?
:
Let x = amt of copper required
then
(70-x) = amt zinc required
:
65x + 30(70-x) = 45(70)
:
65x + 2100 - 30x = 3150
:
65x - 30x = 3150 - 2100
:
35x = 1050
x = {{{1050/35}}}
x = 30 lb of copper
 and
70 - 30 = 40 lb of zinc
;
;
Check solution in original equation 
65(30) + 30(40) = 45(70)
1950 + 1200 = 3150</PRE>