Question

hi friends.....
the diatance between 2 points on a highway is 90km. 2 cars starts from 2 points at the same time in the same direction they meet after 9 hours and when they move in opposite direction they meet after 9/7 hours.. find the speed of 2 cars...

Answer 1

brainliest mark kro bhai plzz..

Answer 2

Let car 1 and car 2 are at a distance of 90 km from each other.

Case 1 (car 1) :
Let car 1 start from point A and car 2 start from point B and they both meet at point C by travelling in the same direction

Time = 9 hrs
Speed = ?
Distance = 90 + y km
We know,
Speed = distance / time
So, speed = 90 + y/ 9 km/hr

Case 1 (car 2) :
Time' = 5 hrs
Distance' = y km
Speed' = ?
Now,
Speed' = y/5 km/hr





Case 2(car 1) :
Let the two cars move in the opposite direction towards each other, they both meet in 9/7 hrs i.e. speed of car 1 = speed of car 2.

Car 1 -
Speed = ?
Distance = x km
Time = 9/7 hr
We get,
Speed = distance / time
Speed = x / 9 / 7
Speed = 7/9 km/hr

Car 2 -
Speed' = ?
Distance' = (90 - x) km
Time' = 9/7 hrs
We get,
Speed' = 90 - x / 9 / 7
Speed' = 7(90-x) / 9 km/hr



Now,
Speed of car 1 = speed of car 1
90 + y / 9 = 7/9
On cross multiplying, we get,
810 + 9y = 63
9( 90 + y ) = 63
90 + y = 7 -------------------- 1

And,
Speed' of car 2 = speed' of car 2, i.e

Y/5 = 7( 90 - x) / 9
Y/5 = 630 - 7x / 9
On cross multiplying we get,
9y = 5 ( 630 - 7x )
9y = 3150 - 35x
9y + 35 x = 3150 ----------------- 2

By using elimination method in 1 and 2 we get,