The boat sailed with the flow for 0.4 hours. He swam for 0.6 hours against the current, swimming only 16.8 km.

The boat sailed with the flow for 0.4 hours. He swam for 0.6 hours against the current, swimming only 16.8 km. With what speed the boat was sailing with the current if it was sailing against the current at a speed of 16 km / h.

Find the distance that the boat sailed against the current;
Let’s multiply the speed by time: 16 km / h * 0.6 h = 9.6 km;
Let’s find the distance that the boat sailed with the current:
16.8km – 9.6km = 7.2km;
Let’s find the speed of the boat when moving with the current:
7.2km / 0.4h = 18km / h.