[Mouse in the Library]

P = A

You were among the first five valid answers, well done - FRKJ

D = L

You were among the first five valid answers, well done - FRKJ

E=S

You were among the first five valid answers, well done - FRKJ

C= T

You were among the first five valid answers, well done - FRKJ

[emmilina]

N = D

[Alessa9]

S=N

[tennisfan]

V = H

M = C

W = E

O = I

[HogwartsExpress]

G = a

Invalid - not the right decryption for this letter - FRKJ

A = P

H=G

[MiaJohn]

G - O

R = U