Chapter 3 - Section 3.2 - Corresponding Parts of Congruent Triangles - Exercises - Page 151: 14

Since $\overline{KJ}$ and $\overline{JL}$ have the same length, then $J$ is the midpoint of $\overline{KL}$

According to Statement 5, $\overline{KJ} \cong \overline{JL}$ Since $\overline{KJ}$ and $\overline{JL}$ have the same length, then $J$ is the midpoint of $\overline{KL}$