Question

( urgent my brother's exam tmrw) 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 towards each other,they meet in 1hour20minutes,find the speed of the cars.

Answer 1

Answer:

a= 35. , b=25

Step-by-step explanation:

Let speed of A be Km/h and speed of B be km/h

And we know that distance =80km

80=(a-b) ×8 and 80=(a+b)×(4/3)

a-b=10 and a+b=60

a= 35. , b=25

(Answer)

Answer 2

Let the speed of car starting from A be 'x' km/h and speed of car starting from B be 'y' km/h.

Total distance=80 km

Also 1 hour 20 mins= 4/3 hour

As per given condition, When car moves in same direction,

Distance travelled by y= 8y km

Distance travelled by x= 8x= 80+8y

Now, Equation formed is 8x=80+8y

=> 8x-8y=80

=> x-y=10 ----(1)

Similarly, For opposite direction,

Distance travelled by x= (4/3)x

Distance travelled by y= (4/3) y

Also total distance covered= 4/3*x+4/3y

=> 80= 4x+4y/3

=> 240= 4x+4y

=> 60=x+y ----(2)

Solving Equation (1) and (2)

60=x+y ----(2)

x-y=10 ----(1)

=> x= 10+y ----(3)

Substituting the value of (3) in (2) we get,

60= 10+y+y

=> 60-10=2y

=> 50=2y

=> 25=y

Also, x=10+y=> x= 10+25=> x=35

Therefore Speed of car starting from A is 35km/h

Speed of car starting from B is 25km/h

Hope it helps!
Best wishes!