For every path from A to B we have two path to return ( As same path cannot be used) Case-1Path from A to B 12 miles

Coming back either using 10 miles or 15 miles

So distance covered can be either

22 or 27 miles

Case-2Path from A to B 10 miles

Coming back either using 12 miles or 15 miles

So distance covered can be either

22 or 25 miles

Case-3Path from A to B 15 miles

Coming back either using 10 miles or 12 miles

So distance covered can be either

25 or 27 miles

In any case ratio of total distance covered will be

22:25:27Answer E.
_________________

Regards;

Vishal

+==========+

Kudos if it deserve....one...