CMOS Inverter output for a given transfer characteristics

I have tried solving the below CMOS problem with a given transfer characteristics but my answer is wrong. Answer should be 0.25. Could someone please point out where I went wrong ?

• I actually agree with you that the answer should be 0.225, are you sure the 0.25 isn't a typo? – Bimpelrekkie Feb 12 at 20:04