Answer:
10 kgs of 25% copper alloy and 40 kgs of 70% copper alloy
Step-by-step explanation:
Let a be kg of 25% copper alloy, and
b be kg of 70% copper alloy
We can write two equations:
1. a + b = 50
2. 0.25a+0.7b=0.61(50)
We can write #1 as b = 50 - a, and then plug it into #2. We have:
0.25a+0.7b=0.61(50)
0.25a+0.7(50 - a) = 0.61(50)
0.25a + 35 - 0.7a = 30.5
-0.45a = 30.5 - 35
-0.45 a = -4.5
a = -4.5 / - 0.45
a = 10
Also, b = 50 - a, so b = 50 - 10 = 40
The metalworker should use 10 kgs of 25% copper alloy and 40 kgs of 70% copper alloy to make it.
