If a pentagon is regular, then all of the sides are the same length. This means that

So, if
, the lengths of the sides evaluate to

So, all the sides of the pentagon are 21 units long, and AB is 21 units long as well, because all sides are the same length.
Assuming 22 degrees
complement means they add to 90 degrees
22+?=90
minus 22 both sides
?=68
answer would be C