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A F.1 Problem (15 Points!)

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Person A drives a car at a speed of 80km/h from city A to city B. At the same time, Person B and Person C drive at a speed of 60km/h and 65km/h respectively from city B to city A. If Gary meets Person B 30 minutes after he has met Person C, find the distance between city A and city B.ANSWER REQUIREMENTS:Full... 顯示更多 Person A drives a car at a speed of 80km/h from city A to city B. At the same time, Person B and Person C drive at a speed of 60km/h and 65km/h respectively from city B to city A. If Gary meets Person B 30 minutes after he has met Person C, find the distance between city A and city B. ANSWER REQUIREMENTS: Full explanation Clear THANKS!!!

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Let the time required for A to meet B be T hrs and that for A to meet C be ( T - 0.5 ) hrs. Next suppose the distance between A and B be d km and as given, 80( T - 0.5 ) + 65( T - 0.5 ) = d 145( T - 0.5 ) = d --- ( 1 ) 80T + 60T = d --- ( 2 ) 140T = d --- ( 2 ) Put ( 2 ) into ( 1 ), 145( T - 0.5 ) = 140T 145T - 140T = 72.5 5T = 72.5 T = 14.5 d = 140( 14.5 ) = 2030 Hence the required distance is 2030km.

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