Ratio

When asked to express a quantity as a fraction of another, look for the phrase "fraction of" and underline/highlight it. The quantity after "of" should be in the denominator.

E.g. 1
Joy is 12 years old and her mother is 35 years old. Express Joy's age as a fraction of her mother's age.
Her mother's age should be in the denominator.
So the answer is 12/35.

E.g. 2
Yvonne has 19 stamps. Tim has 31 stamps. What fraction of Yvonne's stamps is Tim's stamps?
Yvonne's stamps should be in the denominator.
So the answer is 31/19.