If m∠ABC = 70°, what is m∠ABD? Justify your reasoning.

Question

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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

Using the Angle Addition Postulate,40+70 = m∠ABD.So m∠ABD=110 using the addition property

Answer 1

A Subtraction Property of Equality does not exist.

The standard term is Addition Property of Equality that hold for all number, positive and negative.