Points A and B are 70 km a part 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 one hour. Find the speed of the two cars.
Let the speed of car from A be ‘a’ and of car from B be ‘b’
Speed = distance/time
Relative speed of cars when moving in same direction = a + b
Relative speed of cars when moving in opposite direction = a – b
Given, if they travel in the same direction, they meet in 7 hours, but if they travel towards each other, they meet in one hour. A and B are 70 km a part on a highway
⇒ a + b = 70 ------ (1)
Also, a – b = 70/7 = 10 ------ (2)
Adding (1) and (2)
⇒ 2a = 80
⇒ a = 40 km/hr
Thus, b = 40 – 10 = 30 km/hr