38.7% means 38.7/100 = 0.387
30.2 lbs (1 kilogram/2.2 lbs) = 13.73 kilograms
0.387 * 13.73 kilograms
= 5.31 kilograms copper
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A copper alloy is found to be 38.7% copper by mass How many kilograms of copper are present in a 30.2 pound sample? Please show work :)