Distance, rate, and time

Question

The current in a stream is 5 mph. Akiva takes a trip upriver and it takes 6 hours. The trip back downriver takes 5 hours. What is the speed of the boat in still water?

Answer 1

Distance = rate x time

R is the speed of the boat 

 

 

Upstream: against the current.

Slows down the boat.

Distance = (r-5)*6

 

Downstream: with the current.

Speeds up the boat

Distance = (r+5)*5

 

6R-30=5r+25

6R-30-5r-25=0

R-55=0

R=55

 

Upstream: 55-5 mph= 50 mph

         6 hours x 50 mph= 300 miles

 

Downstream: 55+5= 60mph

   60 mph x 5 hours = 300 miles