Math, asked by mridulbirla13, 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 go in opposite directions they meet in 9/7 hours. Find their speeds.

Answers

Answered by dainvincible1
19

 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

Answered by ferrari11
3

Answer:

Step-by-step explanation:

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

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