упростите выражение c^2-6c+9/7c:(3c-9)

(c²-6c+9)/7c:(3c-9)=(c-3)(c-3)/7c:3(c-3)=
=(c-3)(c-3)/7c.(3(c-3))=(c-3)(c-3). 1/7c.3(c-3)=
=(c-3)/21c 
  =======
c≠3,c≠0