Erin is a member of her school’s track team. last week, she ran 8 1/2 laps around the track in 30 minutes. this week, erin ran for
30 minutes at a constant rate of 2 1/2 minutes per lap. how many more laps did erin run this week than last week?

If m∠abc = 70°, what is m∠abd? justify your reasoning.  using the addition property of equality, 40 + 70 = 110, so m∠abd = 110°.  using the subtraction property of equality, 70 − 30 = 40, so m∠abd = 30°.  using the angle addition postulate, 40 + m∠abd = 70. so, m∠abd = 30° using the subtraction property of equality.  using the angle addition postulate, 40 + 70 = m∠abd. so, m∠abd = 110° using the addition property of equality.