SOLUTION: A man completed a trip of 136 km in 8 hrs. Some parts he covered in 15km/hr and some parts he covered in 18km/hr. What is the part he covered in 18km/hr ?

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Question 887423: A man completed a trip of 136 km in 8 hrs. Some parts he covered in 15km/hr and some parts he covered in 18km/hr. What is the part he covered in 18km/hr ?
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Let x km = the part he covered in 15 km/hr
This means 136-x km = the part he covered in 18 km/hr
Since time = distance%2Frate
==> time traveled in 15 km/hr is x%2F15,
and time traveled in 18 km/hr is %28136-x%29%2F18
=> x%2F15+%2B+%28136-x%29%2F18+=+8
<=> %286x%29%2F90+%2B+%285%28136-x%29%29%2F90+=+8
=> %28x%2B680%29%2F90+=+8
<=> x%2B680+=+720
=> x = 40 km
=> 136-x = 96 km.
Therefore he covered 96 km traveling at the rate of 18 km/hr