Personally I would make a single small border 2 1/2" cut, which leave a 2' inch border once it is attached, around the quilt, then using the colors in the quilt, make strips that would be going the same direction of the stripes in the panel. Aslo cutting these at 2 1/2" and make them the length you want to get the width you need, then there really is no math involved. Just an idea though.