Find the HCF of all three numbers and divide each term by it.<br><br>
&bull; HCF of 120, 24, and 72 is 24.<br>
&bull; 120 ÷ 24 = 5<br>
&bull; 24 ÷ 24 = 1<br>
&bull; 72 ÷ 24 = 3<br>
&bull; Simplest form: 5:1:3<br><br>
Final Answer: 5:1:3