The actual answers for the AR test for The Last Song don't appear to be online, but maybe it's just as well, as it defeats the purpose to cheat at such a test.
Cheating means you are not learning, and reading is such an important thing to learn properly, in terms of life skills as well as enriching your life.
Why not just read the book in your own time and then take the practice tests available at quibblo.com/quiz/bUwlvxF/The-Last-Song-Quiz?
The Last Song (2009) by Nicholas Sparks is most likely on the AR tests due to its popularity; it was only knocked off the top of the US bestseller charts by Dan Brown's The Da Vinci Code.
The book became a film in 2010 starring Miley Cyrus, to if you wanted to revise, why not just watch the film version first?
You could also brush up on the plot by reading the overviews available on sites like Wikipedia or Goodreads.com, or join the online Nicholas Sparks official community to get a feel of what others think about the novel.
There's help available on YouTube to improve your reading skills, why not watch this one before you get back to The Last Song?