Lets first establish that time is the same for both Kathy and Dennis and we can therefore assign is the value of <em>t</em>
Kathy is cycling 8km/h faster than Dennis. Therefore if Dennis is doing <em>x </em>km/h Kathy is doing (<em>x</em>+8)km/h
If it takes Kathy<em> t </em>time to cycle for 60 km at (<em>x</em>+8)km/h, we can derive the time <em>t </em>as;
(<em>x</em>+8)* <em>t </em>= 60
<em>t</em> = 60/(<em>x</em>+8)
We can now use this time to establsish how fast Dennis is cycling. Dennis, using a speed of <em>x</em> km/h takes the same time (60/(<em>x</em>+8)) to cycle for 36 km. Therefore;
