Chapter 3.3, Problem 11E

Let $H$

be a subgroup of $G$, let $a$

be a fixed element of $G$, and let $K$ be the set of all elements of the form $ah{a}^{-1}$, where $h\in H$.That is, $K=\left\{x\in G|x=ah{a}^{-1}forsomeh\in H\right\}$

Prove or disprove that $K$ is subgroup of $G$.