For this adjustment: Earned but unbilled fees at August 31 were $1,475.

Is that telling you what the final accounts receivable should be or what they should be reduced by?

This is telling you that you provided a service, but you have not billed your customer yet.

What is the journal entry when you bill a customer for work that has been done?

This is the adjusting entry you need to do.

dr. a/r
Cr. Revenue

What is the adjustment for:

Equipment (2700) is depreciated over 5 years, using the straight line method.

what is the adjustment for:

Equipment (2700) is depreciated over 5 years, using the straight line method.

it depends you want to calculate the depreciation for how many months or years.
For one year, the depreciation expense will be (your asset origianal cost - residual value) / useful life. For month, divide the annual depreciation by 12 then multiply by the number of month you want to recognize the depreciation expense.