Question 358406
A car traveled the first 100 kilometers of a trip at one
speed and the last 135 kilometers at an average of
5 kilometers per hour less. If the entire trip took 5 hours,
what was the average speed of the car for the first part
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first part 100 km -----------x km/h
second part 135 km---------- x-5 km/h

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time first part + time second part = 5 hours
100/x + 135/(x-5)= 5
100(x-5)+135x /x(x-5)=5
100(x-5)+135x =x(x-5)*5
100x-500+135x=5x^2-25x
5x^2-260x+500=0
/5
x^2-52x+100=0
x^2-50x-2x+100=0
x(x-50)-2(x-50)=0
(x-50)(x-2)=0
x=2 OR 50 km/h

speed = 50 m/h
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m.ananth@hotmail.ca