Answer: 67.8°
Explanation:
A quadrilateral's interior angles always add up to 360°.
An equality statement can be set up to satisfy this rule:
103.8+77+111.4+p=360
Collect known values
292.2+p=360
Isolate and solve for p
292.2 (-292.2) +p=360 (-292.2)
p=67.8