Question 1124761
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<pre>
To find the average speed, divide the distance by the time.


For your info:  20 minutes = {{{1/3}}} of an hour,  so the speed is  {{{50/((1/3))}}} kilometers per hour.
</pre>

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For the list of longest tunnels in the world, &nbsp;see this Wikipedia article


https://en.wikipedia.org/wiki/List_of_long_tunnels_by_type