will someone show me how to work out this problem?

A plant asset was purchased on January 1 for $75,000 with an estimated salvage value of $15,000 at the end of its useful life. The current year's Depreciation Expense is $5,000 calculated on the straight-line basis and the balance of the Accumulated Depreciation account at the end of the year is $25,000. The remaining useful life of the plant asset is ??000