Question

Places a and b are 80 kilometre 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 8 hours and if they move towards each other they meet in 1 hour 20 minutes find the speed of the cards

Answer 1

Answer:

Step-by-step explanation: from equation 1.

X-y=10

X=10+y

Putting the value of X so obtained in equation 2 .

X+y=60

10+y+y=60

2y=60-10

Y=25

Therefore X=35

Answer 2

Let the speed of the first car which starts from A = x km /hr

Speed of the second car which starts from B = y km / hr

Time = distance / speed

Distance between two places A andB are 80km d = 80 km

i ) if the cars move in same direction

Relative speed of them = ( x + y )km/hr

Time = 8hr

d = 80km

8 = 80 / ( x + y )

x + y = 80 / 8

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

ii ) if two cars moving opposite direction, Relative speed = ( x - y ) km / hr

Time = 1 hr 20 minutes

= ( 1 + 20 / 60 ) hr

= ( 80/60)

= 4/3 hr

d = 80km

4/3 = 80 / ( x -y )

x -y = ( 80 × 3 ) / 4

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

Add ( 1 ) and ( 2 ) , we get

2x = 70

x = 35

Put x = 35 in ( 1 ) we get ,

y = 25

so,

Speed of the first car = x = 35km/hr

Speed of the second car = 25km /hr

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