<PRE><B>Question 1166067</B>
The total traveling time if the Smiths drove y km at 60 km/h and on the return trip improved their average speed to 80 0 km/h . What is it simplest form 
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average speed to 80 0 km/h ???
If the return speed is 80 km/hr:
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The average speed = 2*60*80/(60+80) = 480/7 km/hr (regardless of the distance)
d = r*t
y = (480/7)*t kms --- t in hours (if y is the round-trip distance)

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