two places a and b are 120 km apart from each other on highway. a car starts from a and another from b at the same time.if they move in same direction,they meet in 6 hours,and if they move in opposite direction,they meet in 1 hour 12 min. .find the speed of each car.this question was taken from which book or which website
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Let,
speed of car at "a" be x kmph
speed of car at "b" be y kmph
dis covered by car at "a" in 6 hours = 6x
dis covered by car at "b" in 6 hours = 6y
Since they are travelling in same direction, sign shouble be negative
6x - 6y = 120
x - y = 20 ------------ (1)
1hr 12 min = 1 12/60 = 72/60 = 6/5 hr
Since they are travelling in opposite directions, sign should be positive.
(6/5)x + (6/5)y = 120
6x + 6y = 120×5
6x + 6y = 20×5
x + y = 100 ------------ (2)
Adding (1) and (2)
we get 2x = 120
x = 60
Putting x = 60 in (2)
we get y = 40
Therefore,speeds cars are 60 km/h & 40 km/h.
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