Why Depreciation and Apportioned Fixed Costs are added back to Annual cash flow

Hi there,

In the F9 text book, relevant costs are not including depreciation and apportioned fixed overheads. But there is the answer for a quetion that I don’t understand.
Question summary:
capital exenditure on purchasing an equipment: $160K
Annual profits: $8K
The profits is after deducting from annual depreciation and annual charge of shared fixed overheads.
The annual depreciation is $40K
The shared fixed overheads is $25K

Question: What are the relevant cash flows for this?
Answer: Depreciation and apportioned fixed overheads are not relevant. Depreciation is not a cash flow and apportioned fixed overheads represent cost that will be incurred anyway.

Then check this, this table buggers me big time:
Estimated profits: 8K
Add back depreciation: 40K
Add back apportioned fixed costs: 25K
Annual cash flows: 8K+40K+25K = 73K

The project’s cash flows to be evaluated are:
Year 0, purchase equiment, (160K)
1-4 year’s cash flow from profits, 73K each year.

My confusing:
If depreciation and fixed overheads are not included in relevant cost for cash flow, why they were added back to profits when it was calculated?

Many thanks!