[tex]m\angle QRX=129^{\circ}[/tex]
1) The best way to tackle this question is to remind ourselves of the Exterior Angle Theorem.
2) The exterior angle theorem states that an exterior angle is equal to the sum of two remote angles within the triangle.
So let's find m∠QRX:
[tex]\begin{gathered} m\angle QRX=49^{\circ}+80^{\circ} \\ m\angle QRX=129^{\circ} \end{gathered}[/tex]
