Answer
$\dfrac{\log_{10}{2}}{\log_{10}{7}}$ or $\dfrac{\log2}{\log7}$
Work Step by Step
Recall the change of base formula (pg. 464):
$\log_{b}{m}=\frac{\log_{c}{m}}{\log_{c}{b}}$
Applying this formula to our equation ($b=7, m=2, c=10$), we get:
$\log_7{2}=\dfrac{\log_{10}{2}}{\log_{10}{7}}$
