Tommy wants to analyze the weight of the students at his school. He measures the weight of 100 randomly selected students in the school. He finds the mean is 80 pounds and the standard of the deviation is 8 pounds. Out of 100 students , how many should weigh between 64 and 96 pounds ?

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.