Idon't know how to give brainliest haha but i'll give 5 stars : )

Angle 4 is congruent to Angle 7 because of the theorem If 2 parallel lines are cut by a transversal then corresponding angles are congruent (Thats the reason for statement 2).  The 3rd statement is correct if the reason for it is not supplementary angles but is angle addition postulate (The reason for the third one is angle addition postulate).  Lastly, the answer isnt transitive property but is substitution propert because you substitute angle 7 with angle 4 (last reason is substitution).

Hope I helped

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225