Answer :
[tex]\frac{6}{13}:\frac{6}{12}=\frac{6}{13}*\frac{12}{6}= \boxed{\frac{12}{13}}[/tex]
[tex] \frac{6}{13} / \frac{6}{12} = \frac{6}{13}* \frac{12}{6} = \frac{72}{78} = \frac{12}{13} [/tex]
Therefore your answer is C. 12/13
Therefore your answer is C. 12/13