Divided into 12 equal parts, there are12-1=1/markers.
Divided into 15 equal parts, with 15- 1= 14 markers.
10÷2= 15÷3
The bisector of 10 and the bisector of 15 are duplicated: 10÷2- 1=4.
12÷4= 15÷5
The bisector of 12 and the bisector of 15 are duplicated: 12÷4- 1=2.
10÷5= 12÷6
10 bisector and 12 bisector repeat: 10÷5- 1= 1.
All three marks are repeated, no.
The symbol1* * has: 9+11+14-4-2-1= 27.
You can cut the rope into 27+ 1=28 segments.