An alloy of zinc, magnesium, and copper contains 80% of copper, 15% of zinc, and 5% of magnesium. The second alloy of copper and magnesium only is melted with the first and the mixture contains 75% of copper, 5% of zinc and 20% of magnesium. What is the percentage of magnesium in the second alloy?
1
25%
2
22.5%
3
30%
4
27.5%
5
24%