I don't understand why you think that the slower boat will travel different distances on the different crossings.
Surely that answer would have marks deducted for unnecessary working?
the fast boat will have a speed of 146.153846m/min.
the fast boat will also have been in motion for 19.5min. It will therefore have travelled a total of 1950m
the fast boat will have a speed of 146.153846m/min.
the fast boat will also have been in motion for 19.5min. It will therefore have travelled a total of 1950m
I think you will find 146.153846m/min x 19.5 equals .....2850M.
So still no answer.