Two friends A and B live 140 km apart. They both drive in a straight line towards each other to meet. If A drives at 80 km/h and B drives at 40 km/h, then how many kilometres apart will they be exactly 45 minutes before they meet?
A70 km
B90 km ✓ Correct
C100 km
D80 km
Correct answer: (B) 90 km
Explanation
They will be 90 km apart 45 minutes before meeting.
Combined closing speed = 80 + 40 = 120 km/h.
45 minutes = 45/60 = 3/4 hour.
The gap before meeting = closing speed x remaining time.
= 120 x 3/4 = 90 km.
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