The first thing in the reason column of a two colum proof is always GIVEN as it always coincide with an established fact which has been stated in the question to be worked on.
Two colum proofs involves using a tabulated format in establishing a conjecture.
Statements or facts are written on one side and the reason why the statement is true is stated in the reason column which is on the opposite side.
Starting a two column proof usually involve stating the the assumptions which are given about the shape or geometry.
Since each statement made requires a reason, then the reason behind the first statement which is based on what is stated in the question is written as GIVEN.
THEREFORE, after the statement given in the question has been established, then other reasons such as distributive, Commutative and other reasons may be used to proof one's solution statement.
Learn more :brainly.com/question/22172471
Do you mean something like y<21?
