Section 15.9: Change of Variables in Multiple Integrals

Use the given transformation to evaluate the integral. \(\iint_R (4x+8y) dA\), where R is the parallelogram with vertices \((-1, 3), (1, -3), (3, -1),\) and \((1, 5); x=\frac{1}{4}(u+v), y=\frac{1}{4}(v-3u)\)