F(1)=f, left parenthesis, 1, right parenthesis, equals 1 1 2 2 3 3 4 4 5 5 6 6 7 7 - 2 -2 - 3 -3 - 4 -4 - 5 -5 - 6 -6 - 7 -7 1 1 2 2 3 3 4 4 5 5 6 6 7 7 - 2 -2 - 3 -3 - 4 -4 - 5 -5 - 6 -6 - 7 -7 y y x x f f

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