Dennis = 12 km'h
Kathy = 20 km/h
Step-by-step explanation:
- Lets first establish that time is the same for both Kathy and Dennis and we can therefore assign is the value of t
- Kathy is cycling 8km/h faster than Dennis. Therefore if Dennis is doing x km/h Kathy is doing (x+8)km/h
- If it takes Kathy t time to cycle for 60 km at (x+8)km/h, we can derive the time t as;
(x+8)* t = 60
t = 60/(x+8)
- We can now use this time to establsish how fast Dennis is cycling. Dennis, using a speed of x km/h takes the same time (60/(x+8)) to cycle for 36 km. Therefore;
x * 60/(x+8) = 36
= 60x/(x+8) = 36
36 (x + 8) = 60x
36x + 288 = 60x
288 = 60x – 36x
288 = 24x
12 = x
Dennis is cycling at 12 km/h
Kathy is doing x + 8
= 12 + 8 = 20 km/h
Learn More:
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