In week 10, the Lions traveled to Minneapolis to play their NFC North rival the Minnesota Vikings. Minnesota took an early lead when Jarius Wright caught a 3-yard touchdown pass from Christian Ponder, and added more points when Blair Walsh kicked a 58-yard field goal. In the second quarter, the Lions scored their only points of the first half when Jason Hanson scored a 41-yard field goal. The Vikings responded with a 23-yard field goal by Blair Walsh. After halftime, the Blair Walsh kicked another 23-yard field goal. The Lions responded with a Brandon Pettigrew caught a 16-yard touchdown pass from Matthew Stafford. In the final quarter, Minnesota's Kyle Rudolph caught a 20-yard touchdown pass from Christian Ponder, and Adrian Peterson ran the ball in for a two-point conversion. The Lions responded when Titus Young caught a 1-yard touchdown pass from Matthew Stafford. The Vikings added to their lead when Adrian Peterson completed a 61-yard touchdown run, then Blair Walsh scored a 33-yard field goal. The Lions scored the game's final points when Calvin Johnson caught an 11-yard touchdown pass from Matthew Stafford.
Question: How many total yards of field goals did Blair Walsh kick in the first half?
Answer: 81