We already know the values of IL, JL and JK.
We can use the value of IL and JL to find IJ. Substract JL from IL to find IJ.
[tex]\begin{gathered} IL-JL=IJ \\ 49-31=IJ \\ IJ=18 \end{gathered}[/tex]
Now, we can add JK to IJ to find IK:
[tex]\begin{gathered} IJ+JK=IK \\ 18+12=IK \\ IK=30 \end{gathered}[/tex]
IK is 30.
