Find the sign on a short post that lists 3 distances to
different locations.
Take the distance to Hovander park, subtract it from 30 and
multiply the result by 10. The subtract that number from the
decimal part of the latitude to get the new decimal part of the
latitude of the cache.
Using the decimal part of the distance to Slater Road, multiply
it by 2, add that number to the decimal part of the longitude.
This cache is in an ammo box, and it contains a log book, and
lots of goodies.
If you end up in the middle of the field, try the Hint.