The ornamental design for a sportstanktop with back pocket, as shown and described.
FIG. 1 is a rear and left-side perspective view of the sports tank top with back pocket showing my new design;
FIG. 2 is a rear-elevational view thereof;
FIG. 3 is a front-elevational view thereof;
FIG. 4 is a right side-elevational view thereof; and,
FIG. 5 is a top-plan view thereof.
The crosshatched pattern, although shown intermittently, is meant to represent fabric, and is understood to be distributed uniformly over the surfaces of the claimed design upon which it occurs.
The short-segmented broken lines represent stitching which is not claimed. The long-segmented broken lines showing a partial human figure and the top of a water bottle in FIG. 1 illustrate the environment in which the design is used, and form no part of the claim.