How to solve a problem of 2 cars left in one direction point and and in the speed of 1 car of 115 km of the h distance between a car of 615 km in 3 hours the distance between them became 540 km. what speed is 2 cars

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615-540=75 (on the distance between a car in 3 hours) 75:3=25 (one so many less the speed of the 2nd car decreased so many) 115-25=90 km/h (speed of the second car)
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