Exercise 13 Page 161

Both of the given angles lie in the same position around different intersection points. Therefore, the angles can be classified as corresponding angles. According to the Converse of the Corresponding Angles Theorem, if the angles are congruent, the lines are parallel.

If these angles are congruent, then the lines will be parallel. Recall that two congruent angles have the same measure. 55=x+25 Let's solve this equation for x. The angles are congruent for x=30. Therefore, for this value of x, we have that l ∥ m.