Upstream and back in T hours, plus a second trip: distance covered in still water in given hours

The same question, asked 2 times: 24 Jul 2023 S1*, 13 Sep 2024 S1. Every wording below, oldest first.

Try each one first, then open its answer.

Question 1
24 Jul 2023 S1
54 $A boat can cover 120 km upstream and back in a total of 30 hours, and 25 km upstream and 40 km downstream in a total of 7 hours. How much distance will the boat cover in 16 hours in still water?$
Tap an option to check your answer.
Question 2
13 Sep 2024 S1
72 $A boat can travel 78 km upstream and back in a total of 32 hours. It can travel 15 km upstream and 52 km downstream in a total of 9 hours. How much distance will the boat cover in 12 hours in still water?$
Tap an option to check your answer.

Question 1