Downstream speed 9 km / h. The current speed is 3 km / h. The boat sailed 27 km along the river and returned back.

Downstream speed 9 km / h. The current speed is 3 km / h. The boat sailed 27 km along the river and returned back. How much time did she spend all the way?

1) Determine the time during which the boat sailed 27 km along the river.
We divide the distance by the speed.
27/9 = 3 hours.
2) Find the double value of the current velocity.
3 + 3 = 6 km / h.
3) Determine how fast the boat was going against the river.
We subtract 6 km / h from the downstream speed.
9 – 6 = 3 km / h.
4) Find the time that the boat spent on the return trip.
27/3 = 9 hours.
5) Determine the total time of movement of the boat.
3 + 9 = 12 hours.
Answer: The boat spent 12 hours for the whole journey.