A reference-and-sense scan computes the two comparator input nodes first, here a fixed V_ref = 6 V from an equal-resistor divider and a sensed V_sense = 8 V, before any decision rule runs. The arithmetic is exact only for the stated reference voltages, sensed voltages, resistances, and rows in the ideal comparator and ideal input-divider model. Real comparators add input offset, hysteresis, noise, finite response time, reference tolerance, probe/calibration limits, finite precision, and measurement uncertainty.
A comparator compares two voltages, so the two input nodes must be computed before the decision. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The reference divider makes a fixed node
The reference divider uses equal resistors, so its output is 6 volts.