Answer:
Statements
∠1 and ∠2 are supp. ⇒ Given
∠3 and ∠4 are supp. ⇒ Given
∠1 ≅ ∠4 ⇒ Given
m∠1 + m∠2 = 180 ⇒ Defintion of supp. angles
m∠3 + m∠4 = 180 ⇒ Defintion of supp. angles
m∠1 + m∠2 = m∠3 + m∠4 ⇒ Substitution property
∠2 ≅ ∠3 ⇒ Subtraction property of equality
Explanation:
First 3 statements are given to you by the problem.
Definition of supplementary angle are angles whose measures add up 180.
In the 6th step we substitute m∠3 + m∠4 in for 180 sense it is equal to 180
Finally we subtract m∠1 and m∠4 from each side sense they are equal.
Your proofs may not be worded the exact same way I worded mine and might have less or more steps, but this should give you the idea of how to solve it.