David starts at a position of x=0 meters at the left side of the front of the classroom. Over the course of the class he walks back and forth in front of the class 15 times, 6 meters to the right, and

David starts at a position of x=0 meters at the left side of the front of the classroom. Over the course of the class he walks back and forth in front of the class 15 times, 6 meters to the right, and then 6 meters back to the left. What is the total distance (in meters) david walks?