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