# math

donna took 3hours to row 18 km upstream. her return trip took 1 hour less. find the rate of rowing in still water and the rate of the current.

let the speed of her rowing in still water be x km/h, let the speed of the current be y km/h
going with the current: speed is (x+y), time = 2 hours
going against the current: speed is x-y, time is 3 hours

so:
2(x+y) = 18 ----> x+y=9
3(x-y) = 18 ----> x-y=6

adding these two gives 2x=15
x=7.5, backsubstitute for y=1.5

great website

How many pounds does an 8ton truck weigh?

1. 👍 0
2. 👎 0
3. 👁 181

## Similar Questions

1. ### Precalc

A ship travels downstream for 36 miles and then makes the same return trip upstream. The trip downstream took 3/4 of an hour less then the trip upstream. If the rate of the current is 4mph find the rate of the ship in still water

asked by Zack on August 8, 2018
2. ### Rate of current and time

A ship travels downstream for 36 miles and then makes the same return trip upstream. The trip downstream took 3/4 of an hour less then the trip upstream. If the rate of the current is 4mph find the rate of the ship in still water

asked by Zack on August 8, 2018
3. ### algebra 2

Kate can row a boat 10 miles per hour in still water. in a river where the current is 5 miler per hour, it take her 4 hour longer to row a given distance upstream than to travel the same distance downstream. Find how long it takes

asked by nancy on December 6, 2015
4. ### Math

5. Nafi can row down a 20-mile stream in 2 hours and can return in upstream in 5 hours. What is his average rate, in miles per hour, for the entire trip?

asked by Nayem on November 26, 2019
5. ### Math

Nafi can row down a 20- mile stream in 2 hours and can return in upstream in 5 hours.What is his average rate,in miles per hour,for the entire trip? a.10/7 b.7/2 c.20/6 d.3 e.40/7

asked by Taijin on February 8, 2018
6. ### Math

Lisa rowed her boat for two miles downstream. The trip took her 20 minutes. She then turned around and rowed back the two miles. It took her one hour to row back upstream. a. At what rate of speed did Lisa row downstream? b. At

asked by Wendy on December 1, 2015

Lisa rowed her boat for two miles downstream. The trip took her 20 minutes. She then turned around and rowed back the two miles. It took her one hour to row back upstream. a. At what rate of speed did Lisa row downstream? b. At

asked by Wendy on December 1, 2015
8. ### Math

Lisa rowed her boat for two miles downstream. The trip took her 20 minutes. She then turned around and rowed back the two miles. It took her one hour to row back upstream. a. At what rate of speed did Lisa row downstream? b. At

asked by Wendy on December 1, 2015
9. ### Math

Lisa rowed her boat for two miles downstream. The trip took her 20 minutes. She then turned around and rowed back the two miles. It took her one hour to row back upstream. a. At what rate of speed did Lisa row downstream? b. At