This is one of two mysteries on the Hotspur Trail in Shrewsbury Battlefield. To solve the cache you will need to solve these coordinates:
N (Rf / 2) ((Yb + Ca) / He) . ((Ds + Zr) / 2) W (B - Li) (Mn + Ar) . ((Og + O) x5)
'/' means 'divided by'.
Good luck!
Amazed at the GC code! GC99000
FTF***Lanvet**FTF