Respuesta :

the sum of the internal angles of a triangle is always equal to 180, so:

[tex]\begin{gathered} \text{let:} \\ x=\text{unknown angle} \\ 50+80+x=180 \\ 130+x=180 \\ \text{solve for x:} \\ x=180-130 \\ x=50 \end{gathered}[/tex]