since the smallest number is 2, and 2 can go into itself and 2 also can go into 10, that is the largest common number
[tex]\frac{2}{10}\div\text{ }\frac{2}{2}[/tex][tex]\begin{gathered} 2\text{ divided by 2 = 1} \\ 10\text{ divided by 2 =5} \end{gathered}[/tex]We can not make the number go any smaller since any number divied by one will equal itself
so that means
[tex]\frac{2}{10}\text{ reduced is }\frac{1}{5}[/tex]