My sister is 19 years old. my brother says that his age minus eighteen is equal to my sister's age. how old is my brother? enter an equation, using b as your variable, to find how old my brother is. the equation is my brother is years old.

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?