Answer:
77
Step-by-step explanation:
Let's let the unknown number be x.
Supplementary angles add up to a total of 180 degrees. Since we already know one angle is 103, this means that:
[tex]103+x=180[/tex]
Subtract 103 from both sides:
[tex]x=77\textdegree[/tex]
So, the measure of its supplementary angle is 77 degrees.
And we are done!
