Construction:-
A fence is to be built to enclose a rectangular area. The fence along three sides is to be made of material that costs $5 per foot. The material for the fourth side costs $15 per foot.
(A) If the area is 5,000 square feet, find the dimensions of the rectangle that will allow for the most economical fence.
(B) If $3,000 is available for the fencing, find the dimensions of the rectangle that will enclose the most area.