SOLUTION: 18. Keiko bicycles 4 km/h faster than Dennis. In the same time it takes Dennis to bicycle 27 km, Deiko can bicycle 39 Km. How fast does each bicyclist travel? Dennis travels ?km/

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: 18. Keiko bicycles 4 km/h faster than Dennis. In the same time it takes Dennis to bicycle 27 km, Deiko can bicycle 39 Km. How fast does each bicyclist travel? Dennis travels ?km/      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 326846: 18. Keiko bicycles 4 km/h faster than Dennis. In the same time it takes Dennis to bicycle 27 km, Deiko can bicycle 39 Km. How fast does each bicyclist travel? Dennis travels ?km/h
Keiko travels ? Km/h

Answer by galactus(183) About Me  (Show Source):
You can put this solution on YOUR website!
Remember that d=rt.
In this case, we want time so we use t=d/r
We are told that there times are equal. One is just traveling faster than the other.
Dennis's time is 27/r
Deiko's time is 39/(r+4)
Since they are equal, we have 27%2Fr=39%2F%28r%2B4%29
27%28r%2B4%29=39r
27r%2B108=39r
108=12r
r=9
So, Dennis is going 9 kph and Deiko is traveling 13 kph.
These types of problems are variations on a theme. Use d=rt and manipulate it accordingly. Since they said their times were equal, we use t=d/r. The distance is given, so all we have to do is solve for the rates by equating the time, t=d/r.
See?.