The histogram below shows the tuition costs for 18 public universities..

The median cost for these 18 universities is within which tuition interval?

A:$9,000-$11,999
B:$0-$2,999
C: $6,000-$8,999
D: $3,000-$5,999

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.