Solution for the first problem

@rmascarenhas @andrielfn @fabioyamate please review.

This is the compiled version for the `tex` file.

![screen shot 2014-07-12 at 10 51 46 pm](https://cloud.githubusercontent.com/assets/611891/3563404/c6a636ea-0a31-11e4-90e1-6af4ff83cd43.png)