But you should be able to see what is going on. This brings up the fact that fractions imply division. We want to reduce fractions when we can, because a reduced fraction is normally much easier to use than the unreduced fraction. A handy way to reduce fractions is to use Euclid's Algorithm . And arithmetic is often easier with decimal fractions.
Percents are decimal fractions.
Division is as easy as multiplication. We may have wanted to name the smaller bag first. Then the ratio is 1 to 3.