To add 3 dollars and 35 cents to 5 dollars and 78 cents, write each amount as a decimal. since 3.35 + 5.78=9.13, the total is 9 dollars and 13 cents. can you add 2 hours 45 minutes to 3 hours 57 minutes by using decimal numbers (2.45 + 3.57)? explain your reasoning.

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.