The speed of the boat against the stream of the river is 11.3 km / h. The speed of the river is 3.9 km / h

The speed of the boat against the stream of the river is 11.3 km / h. The speed of the river is 3.9 km / h. Find your own speed of the boat and its speed with the current.

1. Let’s enter the designation of the boat’s own speed – it is “X”. The speed of the boat upstream of the river is defined as the difference in speed. Let’s compose and solve the equation:

X – 3.9 = 11.3;

X = 11.3 + 3.9;

X = 15.2 (km / h) is the speed of the boat in still water.

2. Let’s find the speed of the boat along the river as the sum of the boat’s own speed and the speed of the current:

15.2 + 3.9 = 19.1 (km / h).

Answer: the boat’s own speed is 15.2 km / h, and its speed downstream is 19.1 km / h.