Question
Places A and B are 20 km apart on the highway. A car
starts from A and another from B at the same time. If the cars travel in the same direction at different speeds, they meet in one hour. If they travelled towards each other, they met in 12 minutes. What are the speeds (in km/h) of two cars?Solution
Let the speed of the car from A be x km/h and from B be y km/h. When they travel in the same direction and meet in 1 hour: x - y = 20 ........(1) When they travel towards each other and meet in 12 minutes: (x + y). 1/5 = 20 x + y = 100........(2) Solving equations (1) and (2): From (1): x − y = 20 From (2): x + y = 100 Add both: 2x = 120, x = 60 Then y = 100 − 60 = 40 Speeds are: Car from A: 60 km/h, Car from B: 40 km/h.
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