So every 12dm
Footprints overlap once.
Every12m
There are four footprints.
Sange ningning
Two grandfathers'
One of them is coincidence.
So it's four (you can see it more clearly on paper)
So 60 footprints are
12*(60/4)=
180dm
The circumference is 18m.
2、4dm
Obviously.
3、 12dm
See 1 for the reason.
What grade is this?