AAI ATC Junior Executive 21 Feb 2023 Shift 2 Paper

The time taken by a boat to cover a certain distance upstream is equal to $\frac{4}{7}$ of the time taken by it to cover three times the same distance downstream. The speed of the stream is 7.5 km/h. How many (total) hours will the boat take to go 42 km upstream and 54 km downstream?