<image>Mr. Wang wants to enclose a rectangular flowerbed as shown in the figure, denoted as $$ABCD$$. One side of the flowerbed utilizes a 20-meter long wall, and the other three sides are enclosed with a total of 36 meters of fencing. Let the length of side $$AB$$ be $$x$$ meters and the length of side $$BC$$ be $$y$$ meters, with the condition that $$BC > AB$$.
$$(1)$$ Find the functional relationship between $$y$$ and $$x$$ (also, directly specify the domain of the independent variable $$x$$);
$$(2)$$ When $$x$$ is how many meters, does the area $$S$$ of the flowerbed become maximal? What is the maximum area?