three envelopes contain a total of six bills. one envelope contains two $10 bills, one contains two $20 bills, and a third contains one $10 and one $20 bill. a label on each envelope indicates the sum of money in one of the other envelopes. it is possible to select one envelope, see one bill in that envelope, and then state the contents of all of the envelopes. which envelope should you choose? (May 1, 2012)