Question

Points A and B are 70 km apart on a highway. A car starts from A and another car starts from B simultaneously. If they travel in the same direction, they meet in 7 hours. But, if they travel towards each other, they meet in 1 hour. Find the speed of each car.

Answer 1

Let the speed of the cars be x km/h and y km/h.

Relative speed in same direction = (x - y) km/h

Relative speed in opposite direction = (x + y) km/h

Now, \(\frac{70}{x+y} = 1\)

=> x + y = 70 .....(i)

and \(\frac{70}{x-y} = 7\)

=> x - y = 10

Solving Eqs. (i) and (ii),

x = 40 km/h and y = 30 km/h