Answer
$\log_b\dfrac{km}{a}$
Work Step by Step
$\bf{\text{Solution Outline:}}$
Use the Laws of Logarithms to write the given expression, $
\log_bk+\log_bm-\log_ba
,$ as a single logarithm.
$\bf{\text{Solution Details:}}$
Using the Product Rule of Logarithms, which is given by $\log_b (xy)=\log_bx+\log_by,$ the expression above is equivalent to
\begin{array}{l}\require{cancel}
\log_b(km)-\log_ba
.\end{array}
Using the Quotient Rule of Logarithms, which is given by $\log_b \dfrac{x}{y}=\log_bx-\log_by,$ the expression above is equivalent to
\begin{array}{l}\require{cancel}
\log_b\dfrac{km}{a}
.\end{array}