General: Gutter Design A long gutter is to be made from a 12-inch-wide strip of metal by...

General: Gutter Design A long gutter is to be made from a 12-inch-wide strip of metal by folding up the two edges. How much of each edge should be folded up in order to maximize the capacity of the gutter? [Hint: Maximizing the capacity means maximizing the cross-sectional area, shown below.]