Question 331275
Let x=amount of regular 10% milk needed
Then 80-x=amount of non-fat milk needed
Now we know that the amount of fat in the regular milk (0.10x) plus the amount of fat in the nonfat milk (0) has to equal the amount of fat in the final mixture (0.03*80).  So our equation to solve is:
0.10x=0.03*80 or
0.10x=2.4
x=24 pounds------amount of regular milk needed
80-x=80-24=56 pounds ----amount of non-fat milk needed

CK
24*0.10=0.03*80
2.4=2.4

Hope this helps---ptaylor