Thank you for reporting, we will resolve it shortly
Q.
A vehicle moving with a speed of $18\, km\, h ^{-1}$ covers in $1\, s$.
Physical World, Units and Measurements
Solution:
$v=\frac{18\, km }{ h }=\frac{18\, km }{ h } \times\left(\frac{1000 m }{1 km }\right) \times\left(\frac{1 hr }{3600 s }\right)$
$=\frac{18 \times 1000}{3600} \frac{ m }{ s }=5\, m / s$