same as before, we look at the denominators, hmmm do a quick prime factoring.
3 = 3 * 1
9 = 3 * 3 * 1
since 9 already contains 3 and 1, we can us that
[tex]\cfrac{\underline{2}}{3}~~ - ~~\cfrac{1}{9}\implies \cfrac{(2)\underline{2}~~ - ~~(1)1}{\underset{\textit{using this LCD}}{9}}\implies \cfrac{4-1}{9}\implies \cfrac{\stackrel{1}{~~\begin{matrix} 3 \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}}{\underset{3}{~~\begin{matrix} 9 \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}}\implies \cfrac{1}{3}[/tex]
