Working on the second half of practice questions and can’t seem to understand this one.

I understand the “X” and being able to control that outcome, however, I don’t get why you wouldn’t group the “1” in the second row with the X that we turn into a “1” to its left. That way you have 3 groups instead of 2.

After you get the answer, I don’t get why on the gate model the “NOT” variables start with a 1 and not a 0.