Riddles, brain puzzles and mathematical problems

[BAndrew]

BONUS:

A strange cult, with a belief that strawberries contain the Elixir of life, have succesfully isolated the gene responsible for producing the flavour in strawberry plants. However, it seems that they have been able to combine this material with bovine DNA to produce a highly infectious virus that affects cattle. Although the viruscauses no harm to the cow, it will cause the milk that it produces to be tainted with a strawberry flavour. Once infected there is no cure and all future generations will produce stawberry flavoured milk. We were able to intercept an encoded message, sent to all members of the cult, regarding a final meeting to discuss the release of the virus. We know that the meeting has been arranged to take place in Athens,
Greece. It is imperative that you decode this cipher so that we can uncover the identity of the mysterious leader of this cult and arrange his arrest.

LFI TIVZG OVZWVI, WLMZOW NXILMZOW, RMERGVH ZOO NVNYVIH GL GSV
URMZO NVVGRMT RM ZGSVMH, TIVVXV.