Speed of the boat 20.4 km / h River speed 3.2 km / h. When the boat passed with the current for 2.5 hours

Speed of the boat 20.4 km / h River speed 3.2 km / h. When the boat passed with the current for 2.5 hours, there was still 16.3 km to the pier. How many kilometers did the boat sail to the pier?

1. The speed of the boat along the river is the sum of its speed in still water and the speed of the river:
v = v0 + u, where
u = 3.2 km / h – river flow speed;
v0 = 20.4 km / h – speed of the boat in still water;
v = 20.4 + 3.2 = 23.6 (km / h).
2. During the time t = 2.5 the boat sailed the way:
s1 = vt = 23.6 * 2.5 = 59 (km).
3. The total path covered by the boat:
s = s1 + s2, where
s2 = 16.3 km – distance to the pier in 2.5 hours;
s = 59 + 16.3 = 75.3 (km).
Answer. Distance to the pier at the initial moment of time: 75.3 km.