Answer: B+E = 180
Angles B and D are corresponding angles. This means D = B since corresponding angles are congruent when we have parallel lines.
Then note how D+E = 180 as these two angles form a straight angle.
Replace D with B getting B+E = 180 (this is the substitution property).
Alternatively, you can say that G = E and B+G = 180 to lead to B+E = 180. There are many other routes to take as well.
