Answer:
Depreciation expense that Grimwood should record is $13,230.
Explanation:
units of activity method:
depreciation rate = (cost - salvage value)/estimated lifetime miles
               = ($171500 - $24500)/(1000000 miles)
               = $0.147 per mile
depreciation expense = $0.147 per mile*90000 miles
                   = $13,230
Therefore, Depreciation expense that Grimwood should record is $13,230.