a rectangular lot whose perimeter is 1600 feet is fenced on three sides. An expensive fencing along the lot's length cost $20 per foot, and an inexpensive fencing along the two side widths costs $5 per foot. The total cost of fencing along the three sides comes to $13000. What are the lot's dimensions?

Answer 1

s = side length
x = long length

2 s + x = 1600 so x = (1600-2s)

2 s (5) + x (20) = 13,000

10 s + 20 (1600-2s) = 13,000

Answer 2

S= 1900/3

X= 1600-(1900/3)