The rule of the average speed is
[tex]A\mathrm{}S=\frac{d}{t}[/tex]d is the distance
t is the time
Since Serina takes 0.25 hour to drive 16 km, then
d = 16 km
t = 0.25 hr
Substitute them in the rule above
[tex]\begin{gathered} AS=\frac{16}{0.25} \\ AS=64\text{ km/h} \end{gathered}[/tex]Her average speed is 64 km per hour
