29. At work your boss states that to calculate cash flow from operations, you need to subtract total cash expenses and taxes paid from total revenues. That is, operating cash flows = revenues cash expenses taxes paid. A co-worker says that this is wrong, as non-cash expenses are also part of total expenses and thus should be deducted from total revenues. Another co-worker adds that there is also no deduction of interest expense, so it understates the tax burden. Provide your explanation.