Question 739405
A metal worker is trying to create a copper alloy .
 He has two different type of metals.
 One is 20% copper and the other one is 60% copper.
 He is trying to make a 52% copper alloy and weighs 80 kg. 
:
let a = amt of 20% copper metal
let b = amt of 60% copper metal
:
The amt equation:
a + b = 80
a = (80-b), use this form for substitution
:
The percent equation in decimal form
.20a + .60b = .52(80)
.20a + .60b = 41.6
replace a with (80-b)
.20(80-b) + .60b = 41.6
16 - .20b + .60b = 41.6
.40b = 41.6 - 16
b = 25.6/.4  
b = 64 kg of 60% copper
:
I'll let you find how much 20% copper is required
check it in the percent equation