Respuesta :

Answer:

t=4h

Steps below

Step-by-step explanation:

We know:

speed of boat with respect to earth:  13  km

speed of stream with respect to earth:  4 km

13 km/h + 4 km/h = 17 km/h The time to travel 68 km with this speed is thus t = 68 km 17 km h = 4 h

Hope this helps.

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