A and B start from a and B at the same time and travel in opposite directions. After 8 hours, the two vehicles meet. It is known that it takes 15 hours for a to complete the whole journey, while B travels 21 kilometers per hour. How many kilometers is the distance between a and B?

A: the distance between a and B is 360 km

A, B two cars at the same time from a, B two places, opposite. 3 hours meet, known a car to complete the whole journey to 8 hours, B car to complete the whole journey in a few hours

qitian0006,
They meet in three hours, and the two cars travel the whole journey every hour
1÷3＝1/3
It takes 8 hours for car a to complete the whole journey
1÷8＝1/8
B car to complete the whole journey:
1 ÷ (1 / 3-1 / 8) = 4.8 (hours)

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