We know the number of yards run per quarter:
- Quarter 1: -2 yards
- Quarter 2: 14 yards
- Quarter 3: -18 yards
- Quarter 4: -6 yards

Sum of yards run across quarters = (-2) + 14 + (-18) + (-6) = -12
Total number of quarters = 4
⇒

⇒
= -3
Hence, he ran -3 yards per quarter