1) Let's sketch this to better grasp it.
As2) angles 1 and 2 are vertical angles, then they are congruent.
As angle 3 is complementary to angle 2, we can write:
m∠2 + m∠3 = 90º
m∠1 = m∠2
71º+ m∠3 = 90º
m∠3 =90 -71
m∠3 =19º
3) Hence, the answer is m∠3 =19º
