PLEASE HELP!

I need help with this problem and I'm not sure where to even start!

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

How can you construct perpendicular lines and prove theorems about perpendicular lines

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.