Find/Determine the function that represents the book value. See I found the other functions but not the BV function it might be a piecewise function.

After Years (m)	Annual Depreciation Rate (Rm) SOY=Years(Years+1)/2Y	Annual Depreciation Amount (Dm)	Book Value (BV m)
Function (X)	Years-X+1Y | Y/YY	Y*(A-Q)	???
1	(5 1 + 1)/SOY = 5/15	(5/15)($135,000 $65,000) = $23,333	$135,000 $23,333 = $111,667
2	(5 2 + 1)/SOY = 4/15	(4/15)($135,000 $65,000) = $18,667	$111,667 $18,667 = $93,000
3	(5 3 + 1)/SOY = 3/15	(3/15)($135,000 $65,000) = $14,000	$93,000 - $14,000 = $79,000 ----------------------------------------- $107,000 $14,000 = $79,000 ^offset $107,000?
4	(5 4 + 1)/SOY = 2/15	(2/15)($135,000 $65,000) = $9,333	$79,000 - $9,333 = $69,667 ----------------------------------------- $93,000 $9,333 = $69,667 ^offset $93,000?
5	(5 5 + 1)/SOY = 1/15	(1/15)($135,000 $65,000) = $4,667	$69,667 - $4,667 = $65,000 ----------------------------------------- $79,000 $4,667 = $65,000 ^offset $79,000?