i need help answering the reasons in geometry

Question

Complete the reasons for the proof.

Given:
m ∠3 = m ∠4

To Prove:
∠1, ∠2 are supplementary

 

https://wca.sooschools.com/media/g_geo_ccss_2016/3/page30a.gif

 

statements                              reasons

m<3=m<4

<2,<3 are supplementary

m<2+m<3=180 degrees

m<2+m<4=180 degrees

m<1=m<4

m<2+m<1=180 degrees

<1,<2 are supplementary

im so confused

 

Answer 1

1) given

 

2) 2 angles making a line

 

3) definition of supplementary

 

4) substitution steps 1 and 3

 

5) vertical angles are =

 

6) sub. steps 4 and 5

 

7) definition of supplementary