the expression 49x² - 36 is equivalent to :
(A) (7x - 6 )²
(B) (7x - 6 ) ( 7x + 6)
(C) (24.5x - 18 )²
(D) (24.5x - 18) (24.5x + 18 )

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.