-Ve feedback comparator and its threshold values?
In this circuit the transistor acts as a switch which shorts R4 or it doesn't.

The approach to finding the levels at which the output switches is to distinguish the two cases:

1) when the transistor is off

2) when the transistor is on

When the transistor is on (case 2) the right side of R3 is connected to ground so you can ignore R4 and R5.

After simplifying the circuit it is simply a matter of finding the situation where the + and - inputs of the comparator have the same input voltage.

Sidenote:

The way the output of the comparator, R6 and the NPN transistor isn't what it should be. If the comparator had an "open collector" or "open drain" output (only pulling the output low) then this circuit would be OK. But the TS332 has a rail-to-rail output. That makes R6 unneeded. Also when the output is high will try to pull the base of the NPN to the supply. This will fail as the TS322's output cannot deliver that much current. There should really be a base resistor in series with the base of the NPN. You can just use R6 so move it so that it's in series with the base of the NPN.