Answer:
60001 miles
Explanation:
Given

Let the cars be:

Assume that Car A has the minimum mileage of x.

The other cars would be:


This implies that Car C has the highest mileage
Required
Determine the possible minimum number of miles
Since the total distance is 180000, then:

Substitute values for Car A, B and C

Collect Like Terms


Divide both sides by 3



The car with the most mileage is Car C
So:

Substitute 59999 for x in



The minimum distance travelled by Car C is 60001 miles