can someone please help me in this assignment I really don't know how to do it

The angles PBC and PBA are supplementary, then it sums 180, so we have the next equation
[tex]\begin{gathered} 5k+12+83=180 \\ 5k=180-83-12 \\ 5k=85 \\ k=\frac{85}{5} \\ k=17 \end{gathered}[/tex]Then, the answer is C.17