Why do we need to deduct gain on sale of plant assets from net income to arrive at net cash flow from operating activities

The money received from the sale of assets is included in the net cash flows from investing activities, that is why you must adjust net income by eliminating any gain or loss resulting from these transactions.  

Explanation:

E.g. net income = $50,000, and it includes a gain of $5,000 resulting from the sale of a truck. The truck had a book value of $15,000, but was sold at $20,000.

Net cash flows from operating activities:

Net income $50,000

Adjustments to net income:

- Gain on sale of asset ($5,000)

Net cash flow provided by operating activities $45,000

Net cash flows from investing activities:

Sale of truck $20,000

Net cash flow provided by investing activities $20,000

d. all of the above are true.

you will have $2593.74 in 10 years if you set aside $1,000 at 10%

you will have $9321.91 in 20 years if you set aside $2000 at 8%

you will have $1469.32 in 5 years if you set aside $1000 at 8%

you will have $1296.87 in 10 years if you set aside $500 at 10%

you will have $239.66 in 15 years if you set aside $100 at 6%

you will have $4660.96 in 20 years if you set aside $1000 at 8%