algorithm - RSA Decryption from Public Key Values -

i'm little stuck trying figure out how decrypt messages , use hints may doing wrong.

i given series of integer values make cipher text. here few of them:

6584 15650 16198 11003

i given following public key b = 3001 n = 18209

so encrypt message m, use formula:

c = m^3001 mod 18209 

i understand encrypt, need find 'd' value satisfies:

bd = 1 mod 18209 3001d = 1 mod 18209 

any hints on technique or algorithm me find suitable value 'd'?

edit: figured out! i'll come , post answer in week or 2 i'm sure professor wouldn't pleased if posted here on public domain while peers continue work on it.