What is the first step in the construction of a perpendicular line from point P to line m?

A.. Construct an arc that intersects line m at two points.

B..Use a straightedge to draw a perpendicular line to line m through point P.

C..Measure the distance from point P to line m.

D. Add a point below line m and connect the points.

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.