Nice QOTD.
I got it right but for different reasons. If you wanted to add an additional wrinkle try:
SELECT @Var2 = ' - ', @Var3 = CONVERT(DATETIME, '01/01/2010', 101),@Var1 = cast(@var3+5 as int);
SELECT @Var1 + @Var2 + @Var3 AS Result1;
If the perception is that this is performing date addition (e.g. Dateadd) the above expected result would be 5, not 2120-01-07 00:00:00.00.
Tim