Resistors in parallel Thevenin circuit

[influx]

When calculating Rth, they took the parallel combo of he 40 kilo ohm and 160 kilo ohm resistors, then they added the 8 kilo ohm resistor that's in series with the combo.

Maybe I'm having a brain freeze or something but how are the 40 kilo ohm and 160 kilo ohm resistors in parallel? They don't have the same voltage across them?

 

[phinds]

When finding a Th equivalent circuit, voltage sources are treated as a short circuit when figuring Rth

 

[NascentOxygen]

When calculating Rth, they took the parallel combo of he 40 kilo ohm and 160 kilo ohm resistors, then they added the 8 kilo ohm resistor that's in series with the combo.

The answer arrived at by this method should be the same as you'd calculate using the open-circuit voltage / short-circuit current approach. This means you can always check your own answer.