Since S is the center, we can conclude:
[tex]\begin{gathered} m\angle QSR=QR \\ so\colon \\ m\angle QSR=84 \end{gathered}[/tex]and:
[tex]\begin{gathered} m\angle QPR=\frac{QR}{2} \\ so\colon \\ m\angle QPR=\frac{84}{2} \\ m\angle QPR=42 \end{gathered}[/tex]
