Choose the best definition for the following phrase: like terms a letter that holds the place for some unknown value in mathematics a process where you must look for terms that have identical variable parts and then combine their coefficients a process where if two things are equal, one can be put in the place of the other and nothing will change terms that have identical variable parts

What is the next step in the given proof? choose the most logical approach. a. statement: m 1 + m 2 + 2(m 3) = 180° reason: angle addition b. statement: m 1 + m 3 = m 2 + m 3 reason: transitive property of equality c. statement: m 1 = m 2 reason: subtraction property of equality d. statement: m 1 + m 2 = m 2 + m 3 reason: substitution property of equality e. statement: 2(m 1) = m 2 + m 3 reason: substitution property of equality