## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$a-b$
Recall: $\log_a(\dfrac{M}{N}) = \log_a M-\log_a N$ Using the rule above gives: $\ln \left(\dfrac{2}{3} \right) = \ln2-\ln3$ With $\ln3 = b \hspace{20pt} \text{and} \hspace{20pt} \ln2=a$, then $\ln2-\ln3 = a-b$ Therefore $\ln \left(\dfrac{2}{3} \right) = \boxed{a-b}$