The man rode a bicycle halfway at a speed of 25 km / h, and the rest of the way went on foot

The man rode a bicycle halfway at a speed of 25 km / h, and the rest of the way went on foot at a speed of 5 km / h. How long did it take if the whole journey took 3 hours?

These tasks: Sv (path by bicycle) = Sп (path on foot) = S / 2; Vv (bike speed) = 25 km / h; Vp (walking speed) = 5 km / h; t (travel time) = 3 hours.

1) Distance traveled: t = tv + tp = Sv / Vv + Sp / Vp = S / 2Vv + S / 2Vp = 3.

3 = S / (2 * 25) + S / (2 * 5).

3 = S / 50 + S / 10.

3 = 6S / 50

S = 3 * 50/6 = 25 km.

2) Duration of walking: tp = S / 2Vp = 25/10 = 2.5 hours.

Answer: A person had to walk for 2.5 hours.