You can't have one without the other! This is a Duality cache. To get the coordinates you need to find the opposite of Yang. (GC58EGN) Then you need to subtract the North 17.XXX and West 55.XXX coordinates with the ones found in the hint on that cache page. Together they will give you the final for YANG.
You can check your answers for this puzzle on GeoChecker.com.
Gur Uvag sbe LVA = Evqr gur jnir gb gur pbeare!
Gur Uvag sbe LNAT vf va LVA