Coming off their divisional road win over the Chiefs, the Raiders went home for a Week 3 AFC West duel with the Denver Broncos.  Oakland would trail in the first quarter as Broncos quarterback Kyle Orton completed a 2-yard touchdown pass to wide receiver Brandon Marshall, followed by kicker Matt Prater's 48-yard field goal.  The Raiders would get on the board in the second quarter as kicker Sebastian Janikowski made a 48-yard field goal, yet Denver answered with Prater's 21-yard field goal.  From here on out, the Broncos were in control as running back Knowshon Moreno got a 7-yard touchdown run in the third quarter and Prater nailed a 24-yard field goal in the fourth quarter.
Question: How many yard field goals did Prater have?
Answer: 21