5. In the triathlon event of the Olympics, the cycling distance is 4 times the running distance, the swimming distance is $\frac{3}{80}$ of the cycling distance, and the difference between the running and swimming distances is 8.5 kilometers. Find the total distance of the three events.
5. The total distance of the three events is 51.5 kilometers.
5.【Solution】Let the distance of cycling be 1, then the distance of running is $\frac{1}{4}$, and the distance of swimming is $\frac{3}{80}$. The difference between the distance of running and swimming is $\frac{1}{4}-\frac{3}{80}=\frac{17}{80}$, which is 8.5 kilometers. Therefore, the distance of cycling is 
$8.5 \div \frac{17}{80}=40$ kilometers, the distance of running is $40 \times \frac{1}{4}=10$ kilometers, and the distance of swimming is $40 \times \frac{3}{80}=1.5$ kilometers, totaling $40+10+1.5=51.5$ kilometers.