Since we know that RP is perpendicular to QS we know that the bisector gives us two right triangles. Furthermore, the bisector divides by two the angle of 104, then the angle SRP is equal to 52°.
Now, we know that the interior angles of any triangle add to 180°. Therefore:
[tex]\begin{gathered} m\angle S+52+90=180 \\ m\angle S=180-52-90 \\ m\angle S=38 \end{gathered}[/tex]