Gallons per day.......gallons / day.....so u put the gallons over the number of days, then divide
(1/2) / 6 = 1/2 * 1/6 = 1/12 of a gallon per day <==
It’s 18, i guess
FG = JHxEF/EJ = 12 + 6 = 18
Let x and y be the dimensions of the rectangle. If the perimeter is 40, we have

We can expression one variable in terms of the others as

Since the area is the product of the dimensions, we have

This is a parabola facing down, so it's vertex is the maximum:

So, the maximum is

And since we know that
, we have
as well.
This is actually a well known theorem: out of all the rectangles with given perimeter, the one with the greatest area is the square.
Isolating 2abCos(c) on one side of the equation and using the given values of a, b and c we can find the answer to this question as shown below: