Math, asked by KawalSurbhi, 1 year ago

Points A and B are 90 km apart from each other on a highway. A car starts from A and another from B at the same time. If they go in the same direction, they meet in 9 hours, and if they move in opposite directions, they meet in 9/7 hours .Find the speed of each car.​

Answers

Answered by rohit1741
6

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

⇒ 1 hour 20 mins= 4/3 hour

given that when car moves in same direction,

∴distance travelled by y= 8y km

∴distance travelled by x= 8x= 80+8y

⇒equation formed is 8x=80+8y

=> 8x-8y=80

=> x-y=10 ..................1

agai for opposite direction,

∴distance travelled by x= (4/3)x

∴distance travelled by y= (4/3) y

⇒total distance covered= 4/3*x+4/3y

=> 80= 4x+4y/3

=> 240= 4x+4y

=> 60=x+y ...............2

from equation 1 and 2 we get

60=x+y ...........2

x-y=10 .........1

=> x= 10+y ..........3

after substituting the value of equation 3 in equation 2

60= 10+y+y

=> 60-10=2y

=> 50=2y

=> 25=y

⇒x=10+y=> x= 10+25=> x=35

∴the speed of car starting from a is 35km/h

∴the speed of car starting from b is 25km/h..

mark as brainlist..


KawalSurbhi: Thanks
Answered by BrainlyHeart751
1

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

hope it helps you mark as brainliest please

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