Need help with this algebra ii question

1. what are the missing reasons in the proof 2. it's in the second picture and 3

Question: a) does the given set of points represent a linear function? how do you know? b) assume that the point (-2,4) lies on the graph of a line. what y-values could complete this set of ordered pairs that lie on the same line: (- (hint: there are several correct answ

Precalculus question, image attached.