Answer:
600 ounces of 20% alloy of copper
Step-by-step explanation:
let the amount be x ounces,
.
20% of x+60% of 200 ounces=30% of (x+200) ounces
[tex]\frac{20x}{100} +\frac{60*200}{100} =\frac{30(x+200)}{100} \\20x+12,000=30x+6,000\\divide~by~10\\2x+1200=3x+600\\3x-2x=1200-600\\x=600[/tex]