In Trina's desk drawer, there are 15 paper clips and 18 rubber bands. In Kirk's office supply tray,

In Trina's desk drawer, there are 15 paper clips and 18 rubber bands. In Kirk's office supply tray, there are 13 paper clips and 16 rubber bands. Who has a higher ratio of paper clips to rubber bands?

Trina: 15/18

Kirk: 13/16

We want common denominators to compare, so we get a greatest common factor (GCF) for 16 and 18.
Running this through our search engine, we get GCF(16, 18) = 144

For Trina, 144/18 = 8
For Kirk, 144/16 = 9

We multiply Trina's fraction, top and bottom by 8:
15 * 8 / 18 * 8
120/144

We multiply Trina's fraction, top and bottom by 8:
13 * 8 / 16 * 8
104/144

Trina has more in her numerator, so her ratio of paper clips to rubber bands is greater.