[tex]Formula\ for\ speed\\\\
v=\frac{s}{t}\\\\
s=18\ feet\\\\
t=2\ seconds\\\\
v=\frac{18}{2}=9\frac{feet}{second}\\\\
1\ foot= 0.000189393939\ miles\\\\
1\ second=\frac{1}{3600}hour\\\\
9\frac{feet}{second}=9*\frac{0.000189393939}{\frac{1}{3600}}=6,156\frac{mile}{hour}\approx6,16\frac{mile}{hour}
[/tex]