Double Integral Over a Parallelogram

Evaluate $\displaystyle \iint_R x\ \mathrm{d}A$ where $R$ is the parallelogram enclosed by the following lines: • $x+y = 1$ • $x-2y = 2$ • $x+y=3$ • $x-2y = 4$ The answer is in the form $\frac{\alpha}{\beta}$ where $\alpha$ and $\beta$ are coprime integers. Input the value of $\alpha+\beta$.