Question 112780
Let x= 20% alloy; y= 27% alloy
Set up system of equations:
.20x+.27y=24.9 
   x+y=100  -->multiply by -.20

 .20x+.27y=24.9
-.20x+-.20y=-20.00
       .07y=4.9
         y=70  -->plug back into one of the original equations

x+70=100
x=30

30 ounces of 20% alloy; 70 ounces of 27% alloy