Question

The distance between two stations A and B is 230 km. Two cars start simmultaneously from A and B in opposite directions and the distances between them after 3 hours is 20 km. If the speed of one car is less then the other car by 10 km/h, find the speed of the other car.

Answer 1

GIVEN:
distance between two stations=230km.
distance between two cars after 3h is 20km.
let the speed of first car be S and speed of second car be =S-10
Solution:
let distance covered by first car be x
So the distan ce covered by the second cars is 210 - x (∵ the Difference of distance between 2 cars is 20 km)
Time Taken by both cars = 3h = distance travelled / speed
3 = x/v ⇒ x = 3v ------ i
Also
(210-x)/(v-10) = 3 ------ ii
On sovling 1 and 2 we get v = 40km/h
The Velocities Of Both the cars are 40km/h and 30km/h respectively.

Answer 2

Solution:-
The both cars travelled the distance in 3 hours = 230 - 20 = 210 km.
Let the speed of the one car be 'x',
Then the speed of the other car will be (x+10) km/h
Both the cars are moving towards each other, 
So, the combined speed = (x + x + 10) km/h = (2x + 10) km/h
Time = Distance/speed
⇒ 3 = 210/(2x + 10)
⇒ 6x + 30 = 210
⇒ 6x = 210 - 30
⇒ 6x = 180
⇒ x = 30
The speed of the one car is 30 km/h, so the speed of the other car will be
30 + 10 = 40 km/h.
Answer.