Question 189947

Let x=amount of 30% solution needed

Amount of pure gold before the mixture(0.30x+0.15*60) has to equal the amount of pure gold after the mixture (0.20(60+x)), so

0.30x+0.15*60=0.20(60+x)  get rid of parens and simplify
0.30x+9=12+0.20x  subtract 9 and also 0.20x feom each side
0.30x-0.20x+9-9=0.20x-0.20x+12-9
0.10x=3  divide each side by 0.10
x=30 oz-------------------amount of 30% solution needed

CK
0.30*30+0.15*60=0.20*90
9+9=18
18=18

Hope this helps---ptaylor