The vertical angle theorem states that the opposite angles formed by two lines that intersect each other are always equal to each other.
Then, if we apply this to the figure shown we can say that by the vertical angle theorem
[tex]\begin{gathered} L1=L3 \\ L2=L4 \\ Meaning\colon \\ L1=45.5 \\ L4=134.5 \end{gathered}[/tex]
