Question 159
An athlete has just completed a triathlon. This competition is divided into three phases: the first is a swimming race, the second is a cycling race and the third is a running race. Knowing that his average speed in the three sections was $3\ \mathrm{Km}/\mathrm{h}$, $30\ \mathrm{Km}/\mathrm{h}$ and $17\ \mathrm{Km}/\mathrm{h}$ respectively, that the total length of the course is $30\ \mathrm{Km}$ and that the time it took him to finish the race was one hour and 40 minutes, determine how long he cycled.