Let x=the mass of 20% copper
Let y=the mass of 60% copper
x+y=80kg
.20x+.60y=.52(80)%
.20x+.60y=41.6%
Substitute or use elimination to find the amounts needed of 20% copper alloy and the amount of 60% copper alloy to make 80kg of 52% copper alloy
break it down-
It's .52(80)%, so 52% of 80 kg
If you're stuck you can try to find y by subtracting 20% of the mass from the percentage. So basically (.20x+.60y=41.6)-.20(x+y=80)
