m∠5 = 142°
Solution:
Line l and m are parallel.
Sum of the adjacent angles in a straight line is 180°.
⇒ 38° + m∠7 = 180°
⇒ m∠7 = 180° – 38°
⇒ m∠7 = 142°
∠5 and ∠7 are corresponding angles.
If two parallel lines are cut by a transversal, then the corresponding angles on the same side are congruent.
⇒ ∠5 ≅ ∠7
⇒ m∠5 = m∠7
⇒ m∠5 = 142°
Therefore m∠5 = 142°.
