Explanation:
Places A and B are 100 km apart on a highway. One car starts from A and another from B at the same time. If the car travel in the same direction at different speeds, they meet in 5 hours. If they travel towards each other, they meet in 1 hour. What are the speeds of the two cars?
Solution :
Let “x km/hr” be the speed of 1st car
Let “y km/hr” be the speed of the 2nd car
Time = Distance/Speed
Speed of both cars while they are traveling in the same direction = (x – y)
Speed of both cars while they are traveling in the opposite direction = (x + y)
5 = 100/(x -y)
x – y = 100/5
x - y = 20
x - y - 20 = 0 ---(1)
1 = 100/(x + y)
x + y = 100
x + y - 100 = 0--b----(2)
x/(100 + 20) = y/(-20 + 100) = 1/(1 + 1)
x/120 = y/80 = 1/2
x/120 = 1/2 y/80 = 1/2
x = 120/2 y = 80/2
x = 60 y = 40
So, the speed of first car = 60 km/hr
Speed of second car = 40 km/hr