Answer:7 years
Step-by-step explanation:
Depreciation per annum
Cost- salvage value/ no of years
$4,000,000-400,000/8
= $450,000
Accumulated depreciation= depreciation per annum * no of year
Therefore no of years
= Cross multiply
Accumulated depreciation/ depreciation per annum
=$ 3,150,000/$450,000
= 7 years.