If m∠abc = 80°, what is m∠dbc? justify your reasoning. a) using the angle addition postulate, 20 + m∠doc = 80. so, m∠doc = 60° using the subtraction property of equality.
b) using the angle addition postulate, 20 + 80 = m∠dbc. so, m∠doc = 100° using the addition property of equality.
c) using the addition property of equality, 20 + 80 = 100, so m∠doc = 100°.
d) using the subtraction property of equality, 80 − 20 = 60, so m∠doc = 60°.