Use proportions by parts to solve. Salad dressing is 3 oz. oil to 2 oz. vinegar. I'm making a 25 oz. batch. How much oil and vinegar will I need?
There are a couple of ways to tackle this question depending on your grade level.
Oil is 3 parts of the total or 3p
while
vinegar is 2 parts of the total that is 2p
So 3p + 2p = 25
5p = 25
so
p=5
now go back to your oil which was 3p or 3(5) = 15 ounces while
vinegar was 2p or 2(5) = 10 ounces.
Hope this helps : )