Answer:

TIME = Distance/speed

So,

t¹=

[tex] \frac{20}{40} = \frac{1}{2} h[/tex]

t²=

[tex] \frac{24}{56} = \frac{3}{7} h[/tex]

t³=

[tex] \frac{27}{45} = \frac{3}{5} h[/tex]

Average Speed =

[tex] \frac{total \: distance}{total \: time} [/tex]

So,

[tex] \frac{20 + 24 + 27}{ \frac{1}{2} + \frac{3}{7} + \frac{3}{5} } [/tex]

= 46.44 km/h