Question

72km/h=?m/s
20m/s=km/h

Answer 1

$\displaystyle \boxed{1km=1000m} \\ \\ \boxed{ 1h=3600s} \\ --- \\ \\72 \frac{km}{h}=72 \cdot \frac{10\not0\not0}{36\not0\not0} = \frac{720}{36} = 20 \frac{m}{s}$