Casey brought 30 cookies to a birthday party and gave away two to each person. Melissa brought 20 cookies to the birthday party and gave away one to each person. Which equation will show when the two girls will have the same amount of cookies left?

Give all possible names for the line shown. calculation tip: lines can be written with either point first.

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.

In a column proof the right column states your reasons