We claim the ornamental design for a sink and vanity, shown and described.
FIG. 1 is a front, top, right side perspective view of a sink and vanity showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines associated with brackets indicate break lines and the appearance of any portion of the sink and vanity between the break lines forms no part of the claimed design; the other broken lines depict portions of the sink and vanity that form no part of the claimed design.