# How do you end up with 1 degree of freedom with one big link connecting 3 other links?

I was reading Modern Robotics by Kevin Lynch et al. and this robot was presented. They had introduced Grubler's formula which assumes independent joint which gives $$dof = 0$$ but this is not the case for the robot and they provide an alternative computation but it isn't clear how they got the values for Grubler's formula for this.

I understand that this is Grubler's formula and this is also from the book.

The part that is unclear to me is what is highlighted in red.