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A boat travels 105 miles downstream and back. The trip downstream took 5 hours. The trip back took 35 hours. What was the speed of the boat in still water? What is the speed of the current?

Respuesta :

retirEEd

Answer:

Step-by-step explanation:

s speed of the boat

c speed of the current

going downstream

s + c = 105 m / 5 hr  = 21 m/hr     ===>         c = 21 - s

going up stream

s - c = 105 m / 35 hr  = 3 m/hr

s - (21 -s) = 3

s - 21 + s = 3

2s  = 3 + 21

s = 24 / 2  

s = 12 m/hr     <--------------- speed of boat  with no current

c = 21 - s                                         12 + 9 = 21      s+c = 21

c = 21 -12                                        12  - 9 = 3        s-c = 3

c = 9 m/hr      <--------------- speed of current

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