Good point. Let's dissect it another way:


So,
20% of Nepalis are of Madheshi origin.
50% of Nepalis are in Terai.

Hence 40% of Nepalis in Terai are of Madhesi origin;
i.e. 60% of Nepalis in Terai are NOT of Madhesi origin.


So, you want to create two Madhesh states, disregarding the fact that majority of people in those states aren't Madhesis?