Walter and the Christmas Candy jar

About a week before Christmas, 2009 there was a party at Aunt Melanie's house.  It was for all of the Bakers.  Like any good Baker party, there was a counting jar.  Tradition has it that whoever guesses the closest amount of candy in the jar will win the contents and an unknown prize.  This year, when Walter walked in to the party, he immediatly got very excited and wanted to participate in this tradition.  He was doing counting jars in school and knew what they were all about.  He promptly got a piece of paper and wrote down his guess.  When the answer was revealed he was only 7 away from the total, and so he won.  For winning he was presented a 100 dollar bill from grandma and got to take the candy home.  However, there was a twist.  Uncle Forrest wanted that candy so badly he was willing to trade something to get the candy from Walter.  He pulled out a wad of bills, ranging from ones to 100's and told Walter to pick a number between 1 and 31.  Walter chose #30, which was a 100 dollar bill.  This raised Walter's total to 200 in winnings.  Next grandma told Walter that if he gave her the money, she would open a savings acount and double the money.  Walter decided that was the best way to use his money, and so he gave it to her.  At the end of the night Walter was $400 dollars richer.