In order to get the answer to this question you must find the number that the numerator and the denominator is dividable by (common factor) then divide.
[tex]\frac{6}{9}[/tex]
[tex]CF=3[/tex]
[tex]6\div3=2[/tex]
[tex]9\div3=3[/tex]
[tex]= \frac{2}{3}[/tex]
Therefore your answer is "2/3."
Hope this helps.