Coming off their road win over the Lions, the Cowboys went home for a Week 15 NFC East rematch with their hated rival, the  Philadelphia Eagles.  After a scoreless first quarter, Dallas shot first with rookie kicker Nick Folk getting a 33-yard field goal.  Afterwards, the Eagles responded with QB Donovan McNabb completing a 1-yard TD pass to WR Reggie Brown.  In the third quarter, the 'Boys tried to catch up as Folk kicked a 23-yard field goal for the only score of the period.  However, in the fourth quarter, Philadelphia extended their lead with kicker David Akers nailing a 21-yard field goal. With the loss, the Cowboys fell to 12-2, but clinched a first round bye with Seattle's loss earlier in the day. In Dallas Cowboys lore, the game became known as "The Jessica Simpson Game," due to the attendance of famous pop star Jessica Simpson, who was dating Cowboys QB Tony Romo at the time. Simpson wore a pink version of Romo's jersey and was frequently shown on camera cheering for her boyfriend. Critics of the Cowboys' performance that day would later suggest, perhaps somewhat facetiously, that the reason for Romo and the team's immense struggles was due to the distraction caused by the famous pop star's presence. This game has also been generally marked as the start of the decline of the Super Bowl caliber team the Cowboys fielded that year, due to the celebrity status the players enjoyed that season, as well as the lack of discipline enforced by head coach, Wade Phillips.
Question: how many yards did akers nail?
Answer: 21