To find his speed, we just have to divide d/v because that's the definition of speed.
[tex]v=\frac{d}{t}[/tex]
Where d = 400 meters and t = 5 minutes.
[tex]\begin{gathered} v=\frac{400m}{5\min } \\ v=80\cdot\frac{m}{\min } \end{gathered}[/tex]
Therefore, the answer is A. 80 m/min.
