how much of an alloy that is 20% copper should be mixed with 500 ounces of an alloy that is 60% copper in order to get an alloy that is 30% copper

how much of an alloy that is 20% copper: 0.20x
should be mixed with 500 ounces of an alloy that is 60% copper: 500(0.60)=300
in order to get: = 
an alloy that is 30% copper: (x+500)(0.30) 

putting them together: 
0.2x+300=(x+500)(0.30) 

which gives us x=1500 ounces 


:)