Question 1188767
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<pre>

Calculate the hypotenuse of the right angled triangle


    c = {{{sqrt(560^2+816^2)}}} = 989.67 kilometers


and then divide it by the rate of 54 km/h  to get the travel time


    {{{989.67/54}}} = 18.33 hours   (rounded).    <U>ANSWER</U>
</pre>

Solved.


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In this solution, I neglect the fact that the Earth surface is spherical, 

and consider it as flat.