In evaluating a double integral over a region $D$, a sum of iterated integrals was obtained as follows:
$$\iint_D f(x,y)\, dA = \int_0^{3} \int_0^{2y} f(x,y)\, dx dy + \int_{3}^{9} \int_0^{9-y} f(x,y)\, dx dy \, .$$
Sketch the region $D$ and express the double integral as an iterated integral with reversed order of integration.

$\displaystyle \int_a^b \int_{g_1(x)}^{g_2(x)} f(x,y)\, dy dx$
$a =$ $b =$
$g_1(x) =$ $g_2(x) =$