Respuesta :

The sum of all the angles in a triangle is always 180°.

We can write the equation and solve for the missing angle:

[tex]31^o+77^o+x=180^o[/tex]

Solving for x:

[tex]\begin{gathered} x=180^o-31^o-77^o \\ \\ x=72^o \end{gathered}[/tex]

The measure of the unknown angle is 72 degrees.