How can I get L1 and L2 in missing vertical angles?

The vertical angle theorem states that the opposite angles formed by two lines that are intersected are always equal to each other
This can be understood in the graph shown as
[tex]\begin{gathered} L1=L3 \\ L2=L4 \\ \text{Meaning} \\ L1=103.1 \\ L2=76.9 \end{gathered}[/tex]