Question 574463
rectangular lot uses 260 feet of fencing and uses a wall as one side.
 An expensive fencing along the lot's length costs $2o per foot and
 an inexpensive fencing along the two side widths cost only $8 per foot.
 The total cost of the fencing along the three sides comes to $3280.
 What are the lot's dimensions (length and width)?
:
Only 3 sides, therefore:
L + 2W = 260
L = (260-2W)

:
Total cost
20L + 8(2W) = 3280
20L + 16W = 3280
Simplify, divide by 4
5L + 4W = 820
Replace L with (260-2W)
5(260-2W) + 4W = 820
1300 - 10W + 4W = 820
-6W = 820 - 1300
-6W = -480
W = {{{(-480)/(-6)}}}
W = +80 ft is the width
then
L = 260 - 2(80)
L = 100 ft is the length
:
:
Check this by finding the cost:
20(100) = 2000
8(2*80) = 1280
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totals: 3280