Without actual circuit values other than Vout=7V and duty cycle=21%, it's hard to give a answer ..
Since first circuit is a buck type I would expect Vi to be greater than Vout - 0.333 volts seems wrong - maybe you meant 33.3V
Second is a boost type - at 21% duty cycle expect Vin to be only slightly less than Vout - say around 6V. I doubt -140V is correct.
Not sure about the third - you could try a simulation and watch what happens with parameter changes. It's obviously negative output with positive input - buck behaviour? Say Vin=30V ????