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.

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?

Multiply sixth of sixty six by a half of ten show step by step method

Since we have computer algebra systems that can solve polynomial division problems for us, why is it necessary to learn how to do these things by hand?