During a running competition, Pedro covered 3/5 of the total distance in the first stage, while in the second stage he covered 3/8 of the total distance. Knowing that this race is 42 km long, what was the total distance covered by Pedro?

1. Start by finding the distance covered in the first stage:
\frac{3}{5} \times 42 = 25.2 \text{ km}.
2. Then, calculate the distance covered in the second stage:
\frac{3}{8} \times 42 = 15.75 \text{ km}.
3. Add both results to find the total distance covered:
25.2 + 15.75 = 40.95 \text{ km}.
4. Since Pedro cannot exceed the total race distance of 42 km, the total distance covered is:
\boxed{40.95}