We have the following:
two angles are supplementary when the sum of these is equal to 180 degrees,
now
[tex]\begin{gathered} 13.<\text{FBC}\rightarrow16.[tex]\begin{gathered} <\text{DBC}=<\text{ABC-}<\text{ABD} \\ <\text{DBC}=180-30 \\ <\text{DBC}=150 \end{gathered}[/tex]
Therefore, 17.
[tex]\begin{gathered} <\text{ABF}=<\text{ABC-}<\text{FBC} \\ <\text{ABF}=180-40 \\ <\text{ABF}=140 \end{gathered}[/tex]
Therefore,
