Solution: let the tree circle x meters, that is, the cross-sectional circumference of the tree is x meters.
10X+3= 12X-3
12X- 10X=3+3
2X=6
X=3
Total length of rope: 3× 10+3=33 (m)
Remaining after eight laps: 33-8×3=9 (m).
Answer: About 8 laps, there are 9 meters left.