Answers

2016-03-17T08:19:40+05:30
Time =5 hours 
let us take x as average speed to cover 150 km 
then x+20 will be the average speed to cover next 200 km
then
150/x+200/x+20=5
5 x square+100 x=350 x+3000
x square-50 x-600=0
by solving the equation 
we get the x=60 km
therefore average speed to cover 150 km=60 km/h
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2016-03-17T08:19:56+05:30
Let the first speed be x
distance covered with this speed 150
another speed is x+20
dist covered is 200
t1=150/x
t2=200/x+20
t1+t2=5
150/x+200/x+20=5
hence we get following quadratic eq
x²-50x-600=0
on solving it we get
x=60
thus its speed in first case is 60km/h
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