hi, Im not sure how to work out whether the zener diodes are on or off for this question. I assume to do this you need to work out voltages between the 5k and 20k resistor and between 20k and 10k but im not sure how. Can anyone please explain?

 

First, solve the voltage divider as though the zeners were not there. Then introduce one zener and solve again. Then take it back out, put the other one in, and solve again. You should then have the values you need to solve with both zeners in place.

 

awesome, thanks a lot