Final answer:
The length of the rope without any knots is 18.75 cm.
Step-by-step explanation:
To find the length of the rope without any knots, we need to divide the total length of the rope by the number of knots tied. In this case, the rope length is 75 cm and there are 4 knots tied. So, the length of the rope without any knots is 75 cm divided by 4 which equals 18.75 cm.