Answer
a) Definition of supplementary
b) Substitution Property
c) Distributive Property
d) Subtraction Property of Equality
e) Division Property of Equality
Work Step by Step
a) Supplementary angles are angles whose measures sum to 180.
b) The Substitution Property allows us to replace a term with another term that is equal to the term.
c) The Distributive Property allows us to combine like terms by adding the coefficients of a variable.
d) 20 was subtracted from each side.
e) Each side was divided by 4.
