Question

point A and B are 80 km apart on a highway 1 car starts from A and another from B at the same time if the car travel in the same direction at different speed they meet in 8 hours if they travel towards Each Other they meet in 1 hour 20 minute what are the speed of the two cars

Answer 1

Sol:
Let the speeds of the cars be x km/hr and y km/hr

Case 1:
When the cars are going in the same direction
Relative speed = x - y
Distance = 100 km
Time = 100 / (x - y) = 5 hrs
x - y = 100 / 5=20
x – y = 20 ------------- (1)

Case 2:
When the cars are going in the opposite direction
Relative speed = x + y
Time =100 / (x + y) = 1 hrs
x + y = 100 ------------- (2)

Solving the equations (1) and (2),
x = 60
y = 40
Hence the speeds of the cars are 60 km/hr and 40 km/hr.

Answer 2

Answer:

Speed of Car A  and B are 35 km / hr and 25 km / hr respectively.

Step-by-step explanation:

Let the speed of car at A is x km / hr and at B is y km / hr

Case 1.

8 x - 8 y = 80

x - y = 10

x = 10 + y ... ( i )

Case 2.

4 / 3 x + 4 / 3 y = 80

x + y = 60

x = 60 - y ... ( ii )

From ( i )  and  ( ii )

10 + y = 60 - y

y = 25

Putting value of y in ( i )

x = 10 + 25

x = 35 .