The circumference of the small ring is
1÷40= 1/40
So the circumference of the big ring is
1÷30= 1/30
Their circumference difference is
1/30- 1/40= 1/ 120
So, the whole journey is
10 ÷1120 =1200 (cm)
1200m =12m
Answer: This distance is 12 meter.