Secure the zipper with a single top stitch on each side. remove the temporary threads.
Stitch the end of the zipper together so it can never come undone. Trim off any extra zipper and fuse the end with heat or glue.
Sew up the rest of the rear seam as close to the zipper as you can.
Fold the seam back on itself and finish ironing it. It's now done. You should probably hand wash it to remove the pen ink from it.
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