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Points ‘A’ and ‘B’ are 70 km apart on a highway. A car starts from ‘A’ and another from ‘B’ at the same time. 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 (in km/hr).
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- 20, 30
- 40, 30
- 30, 50
- 20, 40
Correct Option: B
Let speed of car starting from A be x kmph
and speed of car starting from B be y kmph
Case I
When cars meet at P,
7x = AP = AB + BP = 70 + 7y
⇒ 7x – 7y = 70
⇒ x – y = 10 ...(i)
Case II
When cars meet at Q,
x + y = 70 ...(ii)
On adding these equations,
x = 40 kmph
Putting the value of x in equation (i),
y = 40 – 10 = 30 kmph
