Juan's age, x, is 4 times his age 15 years ago. Which equation represents the statement?

a.) x = 4 ( x - 15 )
b.) x = 4x - 15
c.) x = 4 + 15x
d.) x = 4x + 15

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.