Two cities distance between which 630 km were left towards by 2 buses and met through the 7th hour what speed of the first bus if the speed of the second bus is equal to 40 km hour

172
1) 40*7=280 km passed the second bus in 7 hours 2) 630-280=350 km passed the first bus in 7 hours 3) 350:7=50 km/h the speed of the first bus
285
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