We must look at this question in steps
The first half of the journey is travelled at 40 km/h
Half of 100km is 50 km
Using the formula
Distance = Speed x Time
Speed = Distance / Time
Time = Distance / Speed
We can work out the time:
50km / 40km/h = 1.25 hours
Next we look at the second half of the journey
50km at 80km/h
50km / 80km/h = 0.625 hours
Add together both times to work out how long the entire journey took
1.25 + 0.625 = 1.875 hours
Using the Speed formula from before
Speed = 100km / 1.875 =
53 1/3 km/h or 53.3 recurring km/h
Answer: rational
a rational number is a number that can be expressed by a quotient or a fraction
<span>the abstract science of number, quantity, and space.
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Answer:

Hope this helps! If you need an explanation, I've got you.