[rebmark]

How would the accounting journal entry for this appear?

At the end of the month, the restaurant sold one kitchen oven purchased at the beginning of the month and reported a loss of $360

[Earlier in the problem it states that The restaurant acquired 4 identical kitchen ovens for $10,000. Each oven has a 5-year useful life with a total salvage (residual) value of 400.]

Earlier I got that the monthly depreciation was $160 so I'm also not sure if I should divide that to get the depreciation of one oven or just use that whole number.

[pready]

First you need to calculate depreciation for one month for one oven to get the depreciation up to date.
So the cost of one oven is $2,500 ($10,000 / 4) minus $400 salvage value equals $2,100 depreciable base.

Now take $2,100 and divide it by 5 to get your depreciation for one year, which is $420 per year. To get your depreciation for one month take $420 depreciation per year times 1 divided by 12 months to get one month of depreciation, which is $35

So your adjusting entry will be:
Debit Depreciation Expense for 35
Credit Accumulated Depreciation for 35

This gets your depreciation up to date prior to the sale of one oven.