Sometimes it will, and sometimes it won't.
I reason as follows:
(21 + x) + (30 + 2x) = 51 + 3x has an 'x' term
(42 + x) + (30 - x) = 72 has no 'x' term.
The exterior and an interior angles always add up to 180 degrees.
180-150=One exterior angle
180-150=30
We know that all of the exterior angles add up to 360
360/30= the number of sides
360/30=12
The shape has 12 sides.
Answer:

<h3>
<em><u>2√6</u></em> is the right answer.</h3>