Here
Show sum of interior angles is 180°
[tex]\\ \sf\longmapsto <NBA+<NAB=180[/tex]
[tex]\\ \sf\longmapsto <NAB+103=180[/tex]
[tex]\\ \sf\longmapsto <NAB=180-103[/tex]
[tex]\\ \sf\longmapsto <NAB=77°[/tex]
Vertical angles are supplementary
We need m<NAB
