Answer
$\ln \dfrac{7}{x^3}$
Work Step by Step
Recall the log rules:
(a) $\log_b{p \cdot q} =\log p + \log q $
(b) $\log_b{\dfrac{p}{q}}=\log_b{p} - \log_b{q}$ (Quotient Rule).
(c) $\log{a^n}=n \log x $
(d) $\log_a{a^x}=x $
Use the rule (b) with $ p=7$ and $ q=x^3$ to obtain
$\ln 7- 3 \ln 7=\ln 7-\ln x^3 $
Simplify the second term by applying rule (c) to obtain:
$ \ln 7-\ln x^3= \ln \dfrac{7}{x^3}$
