Check out the attached image. I drew what I think your book is showing. The figure on the left is triangle ABC without any extended segments. The figure on the right has segment AB extended shown in red. This forms the exterior angle x
The rule that connects x, y and z together is the remote interior angle theorem. It says that adding two interior angles is going to be equal to the exterior angle that is not touching either interior angle. The "remote" part means "far away" so just think of the two angles that are furthest way or not touching the exterior angle in question.
In terms of algebra, the rule is
x+y = z
The appropriate response is the third one. A Cartesian organize framework is an arrange framework that determines each point exceptionally in a plane by a couple of numerical directions, which are the marked separations to the point from two settled opposite coordinated lines, measured in a similar unit of length. Each reference line is known as an organize pivot or only hub of the framework, and the point where they meet is its birthplace, as a rule at requested combine (0, 0).
2.08. If you want to round, then it will be 2.09.
Hope this helps! ;)