Question

the speed of a vehicle is 20 m per second it is equal to dash kilometre per hour

Answer 1

Hi !!!

Your question meant to convert m/s to km/h

$1 \: m {s}^{ - 1} = \frac{ \frac{1}{1000} km }{ \frac{1}{60 \times 60}h } = \frac{3600}{1000} km {h}^{ - 1} = \frac{18}{5} km {h}^{ - 1}$


So ...

$20 \: m {s}^{ - 1} = 20 \times \frac{18}{5} \: km {h}^{ - 1} = 4 \times 18 = 72 \: km {h}^{ - 1}$

Your answer is 72 km/h....