A boat has a speed of 20 mph in still water. While traveling on a river at top speed, it went 40 miles upstream in the same amount of time it went 60 miles downstream. Find the rate of the river current.

4 answers

since time=distance/speed,

40/(20-x) = 60/(20+x)
n still​ water, a boat averages 9 miles per hour. It takes the same amount of time to travel 26 miles​ downstream, with the​ current, as 10 miles​ upstream, against the current. What is the rate of the​ water's current?
n still​ water, a boat averages 9 miles per hour. It takes the same amount of time to travel 26 miles​ downstream, with the​ current, as 10 miles​ upstream, against the current. What is the rate of the​ water's current?
plug in the numbers 9 mi/hr, 26 mi, & 10 mi into the equation:
distance 1/(speed + x) = distance 2/(speed - x)
or

26/(9+x)=10/(9-x)

multiply both sides by (9-x)(9+x)

the denominators on either side can be cancelled, which then leaves the equation as
234-26x=90+10x
next, add/subtract like-terms
144=36x
x=4