Section 15.9: Change of Variables in Multiple Integrals

Evaluate the integral by making an appropriate change of variables. \(\iint_R \frac{x-2y}{3x-y} dA\), where R is the parallelogram enclosed by the lines \(x-2y=0, x-2y=4, 3x-y=1,\) and \(3x-y=8\).