The boat sails along the river at a speed of 36 km / h, and against the current – at a speed of 28 km / h.

The boat sails along the river at a speed of 36 km / h, and against the current – at a speed of 28 km / h. How long does it take for the raft to cover the distance of 24 km if it starts moving from the same point as the boat?

Let the boat’s own speed be – X km / h, and the speed of the river flow – Y km / h.

Then, by condition:

X + Y = 36 km / h.

X – Y = 28 km / h.

Let’s solve the system of two equations by the addition method.

(X + Y) + (X – Y) = 36 + 28.

2 * X = 64.

X = 32 km / h.

Then the speed of the river is:

Y = 36 – 32 = 4 km / h.

Let us determine the time it takes for the raft to cover the distance of 24 km.

t = 24/4 = 6 hours.

Answer: in 6 hours.