Answer:
see below
Explanation:
<1 and <2 are supplements
<3 and <4 are supplements
<1 is congruent to <4
∠1 + ∠2 = 180 definition of supplementary angles
∠3 + ∠4 = 180 definition of supplementary angles
∠1 + ∠2 = ∠3 + ∠4 transitive property of equality
∠1 = ∠4 given
∠1 + ∠2 = ∠3 + ∠1 substitution property of equality
∠2 = ∠3 subtraction property of equality
∠2 ≅ ∠4 definition of congruent angles