two train start from the same place at the same time but in opposite directions.their speed are 80km/hr and 90km/hr, respectively.after how long will they be 850km apart.?
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let 1st train covered x distance in time t
then, distance covered by 2nd train in the same time t = 850-x
speed of 1st train = x/t
=> 80 = x/t
=> x =80t .......eq.(1)
speed of 2nd train = (850-x) / t
=> 90t = (850-x)
put the value of x from eq.(1)
=> 90t = 850 - 80t
=> 90t +80t = 850
=> 170t = 850
=> t = 850/170 = 5 hr
hence, after 5hr they are 850km apart from each other
I hope this helps you....
then, distance covered by 2nd train in the same time t = 850-x
speed of 1st train = x/t
=> 80 = x/t
=> x =80t .......eq.(1)
speed of 2nd train = (850-x) / t
=> 90t = (850-x)
put the value of x from eq.(1)
=> 90t = 850 - 80t
=> 90t +80t = 850
=> 170t = 850
=> t = 850/170 = 5 hr
hence, after 5hr they are 850km apart from each other
I hope this helps you....
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