Customer: Currently I am paying £60.00 a month for my service. I would like to upgrade to the £80.00 service package because my new employer offers a 20% discount with your company. What would be the cost difference compared to what I am paying now if I upgraded? Employee: With your discount you would only pay a month more for the upgraded plan.

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