Question

Places A and B are 80km apart from each other on a highway. A car starts from A and another from B at the same time. If they move in the same direction they meet in 8hours and if they move in toward each other they meet in 1hour 20mins. Find the speed of the cars.

Answer 1

Answer:

35 km per hour and 25 km per hour

Step-by-step explanation:

x1=speed of the 1st car

x2=speed of the 2nd car

1 hour 20 mins=$\frac{4}{3}$hours

if they move in same direction:

(x1-x2)×8=80

x1-x2=10

if they move in toward each other:

(x1+x2)×$\frac{4}{3}$=80

x1+x2=10

$\left \{ {{x1-x2=10} \atop {x1+x2=60}} \right.$

2x1=70

x1=35

x1-x2=10

x2=25

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 .