This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
The given answer of x = 3 and y = 4 is correct. In the expression "y++ ", ++ is used as a post increment so x is first assigned the value of y (ie 3) then y is incremented (ie to 4). You would be correct if the expression used the ++ as a preincrement (ie x = ++y