If anyone can answer these questions that would help a lot. Besides 13 and 14

In the coordinate plan (-6,9) b (3,9) c (3,3) def is shown in the coordinate plan below

To solve the system of equations below, grace isolated the variable y in the first equation and then substituted into the second equation. what was the resulting equation? 3y=12x x^2/4+y^2/9=1

Given: and prove: what is the missing reason in the proof? given transitive property alternate interior angles theorem converse alternate interior angles theorem