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Part of 2021 Durer Math Competition (First Round)

Problems(1)

Albrecht wants calculate the speed of the car

Source: 2021 Dürer Math Competition Regional E1 https://artofproblemsolving.com/community/c2773609_2021_

1/7/2022
Albrecht is travelling in his car on the motorway at a constant speed. The journey is very long so Marvin who is sitting next to Albrecht gets bored and decides to calculate the speed of the car. He was a bit careless but he noted that at noon they passed milestone XYXY (where XX and YY are digits), at 12:4212:42 milestone YXYX and at 11pm they arrived at milestone X0YX0Y. What did Marvin deduce, what is the speed of the car?
number theory