Question

how much time would it take for an airplane to reach its destination if it traveled at an average speed of 790 kilometers/hours for a distance of 4700 kilometers? what is the airplanes speed in miles/hours?

Answer 1

If the airplane covered 790 kilometers along the ground every hour,
and if it could keep that up, and if there was no wind, and if the
airplane pointed its nose directly toward its destination and never
zigged or zagged even the slightest bit, then it would cover
790 kilometers of the distance during the first hour, another
790 kilometers of the distance during the second hour, another
790 kilometers of the distance during the third hour, 790 more
kilometers of the distance during the fourth hour, and so forth
and so on until it had arrived at its destination.

The minimum time it would need for the total trip would be

           (4,700 kilometers) / (790 kilometers per hour) =

                               5.9494... hours (rounded)

                           5hours 56m  57.7seconds  (rounded) .

(790 kilometers) x (1 mile / 1.609344 kilometers) =  490.88 miles (rounded)

Answer 2

$t = \frac{ \Delta S}{ \Delta V} \\ \\ t = \frac{4700}{790} \\ \\ t \approx 5.95 hours.$

1 kmph is approx. 0.6214 mph.
Then.. 790 will be approx. 490 mph.