Evaluate $\displaystyle \int\int_Re^{\frac{x-y}{x+y}}$ where $\displaystyle R=\{(x,y)\in\mathbb{R}^2:0\leq x,0\leq y,x+y=1\}$ using $\displaystyle x-y=u,x+y=v$.

I got $\displaystyle \frac{1}{2}\int_0^2\int_u^1e^{\frac{u}{v}}dvdu$ but maple says im wrong.