Brass is an alloy created using 80% copper and 20% zinc. if henri's brass trumpet contains 48 ounces of copper, how many ounces of zinc are in the trupmet

We know that the ration/percentage that brass is made of remains the same no matter what the weight is; 

Therefore, 48 ounces are 80% of the trumpet. 

48/80= 0.6 ounce per percent of the zinc (I divided the weight by the percent) 

0.6 ounces × 20%= 12 ounces 

Therefore, there are 12 ouches of zinc in Henri's trumpet. 

Hope I helped :)