please show the equations used. having a table without the values explained is useless to me. Thank you !

JET FAB bought a CNC laser cutting machine at a cost of s750,000 to meet the specific needs of customer that had given a 4-year contract with the possibility of extending the contract for another 4 years. The company uses the MACRS depreciation method for this equipment as a 7-year property for tax purposes. The income tax rate for the company is 42%, and the company expects to have an after-tax rate of return of 8% in all its investments. The generated an annual income of $250,000 for the first four years. The customer laser cutting machine its control. Consequently, the decided not to renew the contract after 4 years due to circumstances beyond if the company obtained ended up selling laser cutting machine for 000. Determine the expected after-tax rate of return on this equipment