First all the operations are performed and the expression is simplified to:

63k^2 +36k - 27 =

Then we pull '9' in front of brackets:

= 9(7k^2 + 4k - 3)=

Split the middle term '4k' in two terms: '4k' = 7k - 3k = -3k + 7k' that is:

= 9(7k^2 - 3k + 7k - 3) = 

Pull 'k' in front of brackets for '7k^2 - 3k':

= 9(k (7k - 3) + (7k - 3)) = 

Pull '(7k - 3)' in front of brackets:

= 9(7k - 3)(k + 1)

Thus, the solution is

63k^2 +36k - 27 = 9(7k - 3)(k + 1)