#### Answer

$20k$

#### Work Step by Step

Removing the grouping symbols and then combining like terms, the given expression, $
5k-(5k-[2k-(4k-8k)])+11k-(9k-12k)
,$ simplifies to
\begin{array}{l}\require{cancel}
5k-(5k-[2k-4k+8k])+11k-9k+12k
\\\\=
5k-(5k-2k+4k-8k)+11k-9k+12k
\\\\=
5k-5k+2k-4k+8k+11k-9k+12k
\\\\=
20k
.\end{array}