Answer
$4 \text{ mph}$
Work Step by Step
Let $x$ be the speed of the walker. Then the speed of the jogger is $x+3.$
Using $D=rt,$ then for the jogger,
\begin{array}{l}\require{cancel}
14=(x+3)t
\\\\
\dfrac{14}{x+3}=t
.\end{array}
Using $D=rt,$ then for the walker,
\begin{array}{l}\require{cancel}
8=xt
\\\\
\dfrac{8}{x}=t
.\end{array}
Equating the two expressions of $t$ and using the properties of equality, then
\begin{array}{l}\require{cancel}
\dfrac{14}{x+3}=\dfrac{8}{x}
\\\\
14(x)=8(x+3)
\\
14x=8x+24
\\
14x-8x=24
\\
6x=24
\\
x=\dfrac{24}{6}
\\\\
x=4
.\end{array}
Hence, the speed of the walker, $x,$ is $
4 \text{ mph}
.$
