Which of the following statements does not describe the structure of an atom? A) An atom has a small, dense center called the nucleus.
B) Inside the nucleus of an atom are protons and electrons.
C) Protons are positively charged sub-atomic particles.
D) Electrons are negatively charged sub-atomic particles.

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.