Which math rule tells you which fraction is greater one third or one fourth?

Answer 1

In general, to compare two fractions, convert to a common denominator. 1/3 = 4/12, and 1/4 = 3/12.

Specifically, if the numerator is the same, dividing by a larger number produces a smaller result, so 1/4 (one divided by four) is less than 1/3.