Solve a mathematical riddle to open the cache.
This geocache should be easy to find. However you need to solve the riddle to open it. It involves GCSE level mathematics. The geocache is under a distinctive beech tree which has fallen down and taken fresh roots from its branches. The hint is for the riddle, not to help find the cache.
Gur evqqyr vaibyirf qvssrerag ahzore onfrf. Gur nafjre vf n ovanel ahzore.