Jillian's Jubilant Juices Café is open 7 1/2 hours during the day. The café keeps one waiter onthe job at a time. Each waiter's shift is 1 1/2 hours long.
How many shifts does Jillian's Jubilant Juices have per day?

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.