Two trains on parallel tracks, same direction, lengths and speeds: time to cross each other

The same question, asked 2 times: 18 Jul 2023 S1*, 20 Jul 2023 S1. Every wording below, oldest first.

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Question 1
18 Jul 2023 S1
63 $Two trains P and Q of lengths 320 m and 540 m, respectively, are running in the same direction on parallel tracks at 108 km/h and 144 km/h, respectively. How much time will the trains take to cross each other completely?$
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Question 2
20 Jul 2023 S1
57 $Two trains of length 130 m and 120 m are running on parallel lines in the same direction at a speed of 40 km/h and 50 km/h, respectively. In how much time will they pass each other?$
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Question 1