What is the term-to-term rule for this sequence: 64, 16, 4, 1, 0.25, …?

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

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.

I'm a polygon i have no parallel lines i am formed 3 line segments i have one right angle two of my angles are angles what am i