Chapter 15 - Multiple Integrals - 15.10 Exercises - Page 1071: 1

$16$

Here, we have $\dfrac{\partial x}{\partial u}=5$ and $\dfrac{\partial x}{\partial v}=-1$ Also, $\dfrac{\partial y}{\partial u}=1$ and $\dfrac{\partial y}{\partial v}=3$ Now, $Jacobian =\begin{vmatrix} 5&-1\\1&3\end{vmatrix}=15+1=16$