Application of Green's Theorem

Hi, I'm trying to answer the following question:

http://imageshack.us/m/849/9551/greenstheorem.png

Basically, I know that you have to use Green's Theorem:

$\displaystyle \displaystyle\oint_C P(x)dx +Q(x)dy = \displaystyle\iint_A (\frac{\partial Q}{\partial x} - \frac{\partial P}{\partial y})\ dx\,dy$

Which makes our integral:

$\displaystyle \displaystyle\iint_A x \ dx\,dy$

My problem is, I don't know how to calculate the limits for the area A. Do we use a parameterisation, or are the limits simply the points of intersection of the functions.

Any help is immensely appreciated.

Thanks :)