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A boat travels 60 miles upstream in 15 hours. The same boat makes a return trip downstream in 6 hours. Find the speed of the boat int the river

Let $$V_b$$ be the speed of boat on still water

Let $$V_w$$ be the speed of flowing water

UPSTREAM - This means that the boat is moving againts the current (Flow of water).

Thus; $$V_u = V_b - V_w$$. As the boat moves up, the water is reducing its speed.

DOWNSTREAM- This means that the boat is moving with the current (Flow of water).

Thus; $$V_u = V_b + V_w$$

$$V_u = \frac{distance travelled, s}{Time of travel, t} = \frac{60}{15}$$

$$V_u = 4 mph$$

$$V_d = \frac{60}{6} = 10 mph$$

$$4 = V_b - V_w$$

$$10 = V_b + V_w$$

Add the two equations: $$14 = 2 V_b$$

$$V_b = 7 mph$$ Answer