CLAIM The ornamental design for a seat and back rest for a chair, as shown and described.
FIG. 1 is a perspective view showing the front, left side and front of a seat and back rest for a chair which forms my new design, the broken lines in this and other figures showing other parts of the chair being for illustrative purposes only and forming no part of my design;
FIG. 2 is an enlarged left side elevational view thereof;
FIG. 3 is an enlarged right side elevational view thereof;
FIG. 4 is an enlarged top plan view thereof; and,
FIG. 5 is an enlarged front elevational view thereof.
The short, broken lines on the chair in FIGS. 1-5 are understood to represent stitching.