Tickbox Quiz #6 Question 1

Why do we not have enough information to say these two are equal? Greg just says we don’t have enough information and moves on, but I don’t understand what could be unknown that would make this statement untrue.

Hi, please see this: https://www.reddit.com/r/GRE/comments/1dfiiw6/prepswift_uant_tickbox_quiz_6_algebra/