Solve a problem in two ways. What of these ways is more rational? From Moscow and Tver to St. Petersburg on the same highway two cars left Moscow and cargo, automobile from Tver, at the same time. Speed of the lorry is 50 kilometers per hour. What speed of the passenger car if it caught up cargo in 7 hours after departure, distance from Moscow to Tver with 168 km?

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1 way: 1) 168:7=24 (km/h) - the speed of rapprochement 2) 50+24=74 (km/h) - speed an automobile 2nd way: 1) - passed 50*7=350 (km) cargo 2) 168+350=518 (km) - passed automobile 3) 518:7=74 (km/h) - speed automobile
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Answer add