code: public static double getPixelXSize(BoundingBox webMercatorBoundingBox,
  			long matrixWidth, int tileWidth) {
  		double pixelXSize = (webMercatorBoundingBox.getMaxLongitude() - webMercatorBoundingBox
  				.getMinLongitude()) / matrixWidth / tileWidth;
  		return pixelXSize;
  	}
docs: Get the pixel x size for the bounding box with matrix width and tile
  width
  
  @param webMercatorBoundingBox
  web mercator bounding box
  @param matrixWidth
  matrix width
  @param tileWidth
  tile width
  @return pixel x size