document.write( "Question 1076579: In an alloy of 150 pounds of zinc and copper, there are 100 pounds of copper. How much copper must be added so that the alloy may be 10% zinc? \n" ); document.write( "
Algebra.Com's Answer #691195 by Boreal(15235)\"\" \"About 
You can put this solution on YOUR website!
The fraction is Zn/Cu+Zn
\n" ); document.write( "right now it is 50/150, if 150 pounds of both and 100 pounds of Cu, the rest has to be Zn. Let x=pounds of copper added
\n" ); document.write( "50/(100+x+50)=0.1
\n" ); document.write( "50/(150+x)=0.1
\n" ); document.write( "50=15+0.1x
\n" ); document.write( "35=0.1x
\n" ); document.write( "x=350 pounds of copper
\n" ); document.write( "At that point, the alloy will weigh 500 pounds, 50 of which will be zinc.
\n" ); document.write( "
\n" ); document.write( "
\n" );