Answer :

Given: places A and B are 80 km apart form each other on a highway. A car starts from A and other from B at the same time. If they move in the same direction, they meet in 8 hours and if they move in opposite directions, they meet in 1 hour and 20 minutes.
To find: the speeds of the cars.
Solution:
Let the speed of car from A be ‘a’ and of car from B be ‘b’.


Speed = distance/time


Relative speed of cars when moving in same direction = a + b


Relative speed of cars when moving in opposite direction = a – b


Given, places A and B are 80 km apart form each other on a highway. A car starts from A and other from B at the same time. If they move in the same direction, they meet in 8 hours and if they move in opposite directions, they meet in 1 hour and 20 minutes.


⇒ a – b = 80/8 = 10 ------ (1)


       


Adding (1) and (2)
⇒ a - b + a + b = 10 + 60


⇒ 2a = 70


⇒ a = 35 km/hr

Put the value of a in (1).

Thus, b = 35 – 10 = 25 km/hr


Hence, speed of two cars are 35km/h and 25 km/h

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