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.

Matching exercise

Match the items on the right to the items on the left.

STEP 1

STEP 2

STEP 3

STEP 4

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