Question 1099109
rate * time = distance.


let r = rate and t = time and d = distance


going downstream, the formula becomes (r+3) * 5 = d
coming back upstream, the formula becomes (r-3) * 8 = d


the distance downstream is the same as the distance upstream, so (r+3) * 5 = (r-3) * 8


simplify to get 5r + 15 = 8r - 24


subtract 5r from both sides of this equation and add 24 to both sides of this equation to get 39 = 3r


solve for r to get r = 39/3 = 13


he paddles at 13 kilometers per hour.


going downstream, the stream adds 3 kilometers per hours to this to get 16 kilometers per hour for 5 hours = 80 kilometers.


coming back upstream, the stream subtracts 3 kilometers from this to get 10 kilometers per hour for 8 hours = 80 kilometers.


the distance downstream and upstream is the same at 80 kilometers.


the speed of the boat is 13 kilometers per hour