Chapter 4 - Inverse, Exponential, and Logarithmic Functions - 4.4 Evaluation Logarithms and the Change-of-Base Theorem - 4.4 Exercises - Page 456: 22

$\approx 0.3503$

Apply logarithmic property : $\log (\dfrac{m}{n})=\log m-\log n$ Re-write as: $\log (\dfrac{643}{287})=\log 643-\log 287$ Now, take logarithmic to the base $10$ and evaluate the result. Therefore, our answer is: $\log_{10} (\dfrac{643}{287})=\log_{10} 643-\log_{10} 287 \approx 0.3503$