Equivalent expressions with common denominators

At a science museum, Julia compares the length of a T-rex tooth and a crocodile tooth. The T-rex tooth is $\blueD{\dfrac{7}{12}}$start color #11accd, start fraction, 7, divided by, 12, end fraction, end color #11accd foot long. The crocodile tooth is $\greenD{\dfrac1{4}}$start color #1fab54, start fraction, 1, divided by, 4, end fraction, end color #1fab54 foot long.