So I found that the Jacobian is equal to $1$. Then I found the bounds and then I found the integral by plugging in $u$ and $v$ for $x$ and $y$ and I integrated this:
$$\int _6^{10}\int _1^3(u+3v)dudv=208.$$
But $208$ is not the correct answer. What part of my setup is wrong? Thanks.
Best Answer
You exchanged the order of integration. $y=v$ ranges from $1\to3$ and $x+2y=u$ ranges from $6\to10$.