First, we take out a square piece of paper, then fold it in half along the diagonal, and fold the left corner horizontally along the dotted line. Then we fold the right corner to the left in the same way.

Then we fold a big triangle on it along the dotted line, and fold another big triangle on us to the back. Fold the paper into the picture below, then put your hand in the mouth of the bag and let the whole bag bulge.

Finally, we make the bottom of the bag into such an arc, and the whole shape is the same as that of the carton for holding French fries.