Exercise 64

In evaluating a double integral over a region \(D\), a sum of iterated integrals was obtained as follows: \(\iint_D f(x, y) dA = \int_0^1 \int_0^{2y} f(x, y) dx dy + \int_1^3 \int_0^{3-y} f(x, y) dx dy\). Sketch the region \(D\) and express the double integral as an iterated integral with reversed order of integration.