To find the total length of the trip, we can use the information that 30 miles represents 60% of the total distance. Let $x$ be the total distance.

We can set up the equation:

$0.6x = 30$

To solve for $x$, divide both sides by 0.6:

$x = \frac{30}{0.6} = 50 \text{ miles}$

Thus, the whole trip is 50 miles.

If you have any questions or need further details, feel free to ask! Here are some related questions you might consider:

1. How many miles are left to travel?
2. If they travel at 10 miles per hour, how long will it take to complete the trip?
3. What percentage of the trip would 25 miles represent?
4. How far would they have traveled if they completed 80% of the trip?
5. If the trip were 100 miles long, how far would they have traveled at 60% completion?

Tip: When calculating percentages, remember that you can convert the percentage to a decimal by dividing by 100.