Property, Plant, and Equipment Our property, plant, and equipment, net, consists of the following:

December $31($in millions$)$ Current Year Prior Year

Machinery, equipment, vehicles, and office furniture $$13,558$ $$9,953$

Tooling $2,5792,188$

Leaseholder improvements $2,3661,826$

Land and buildings $7,7514,675$

Computer equipment, hardware and software $2,0721,414$

Construction in progress $4,2635,559$

$32,58925,615$

Less: Accumulated depreciation $(9,041)(6,731)$

Total $$23,548$ $$18,884$

Depreciation expense was $$2,420$ million and $$1,910$ million for the current and prior years, respectively.

a$.$ Compute the average useful life of Tesla$$s depreciable assets at the end of the current year.

Note: Round answers to the nearest dollar, if applicable.

$ millions Numerator Denominator Average Useful Life

Current year: Answer $1$

$23,548$

Answer $2$

$2,420$

$9\mathrm{.}73$

b$.$ Estimate the percent used up of Tesla$$s depreciable assets at the end of the current year.

Note: Round answers to the nearest dollar, if applicable.

$ millions Numerator Denominator Percent Used Up

Current year: Answer $3$

$9,041$

Answer $4$

$23,548$

$38\mathrm{.}4$