SOLUTION: A Cyclist covers a certain distance in 3.5 hours.If first half of the journey is covered in 20 km/hr and the rest of the journey in 15 km/hr,find the total distance of the whole jo

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Question 781727: A Cyclist covers a certain distance in 3.5 hours.If first half of the journey is covered in 20 km/hr and the rest of the journey in 15 km/hr,find the total distance of the whole journey.
PLease help me!!
THE answer is:60 km
Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
r*t=d for rate multiplied by time equals distance.
t=d/r and we have the d cut into 0.5d%2B0.5d.

First half: 0.5d%2F20, hours
Second half: 0.5d%2F15, hours

The sum of those times must be 3.5 hours.
highlight%280.5d%2F20%2B0.5d%2F15=3.5%29
0.5d%281%2F20%2B1%2F15%29=3.5
d%283%2F60%2B4%2F60%29=3.5%2F0.5
d%287%2F60%29=7
d%287%2F60%29%2A%2860%2F7%29=7%2860%2F7%29
As You Were Told as Key.