By bringing them both to the same/common denominator.

1/4 and 1/3

Which is larger? 12 is the common denominator here and to convert the fraction we multiply them by a form of 1.

3***1/**3***4** = ** 3/12**

4***1**/4***3** =** 4/12**

**By this method we see that 1/3 is larger than 1/4**