Adam is three years older than Joe. After three years, Adam's age will be four years less than two times Joe's age. Considering Adam's present age as x years and Joe's present age as y years, write a pair of linear equations to model the above situation.

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?