Please get me the right answer

I posted this question 2 times and both of the experts had the wrong answer.

Please provide me the excel formulas.

Better Mousetraps has developed a new trap. It can go into production for an initial investment in equipment of $6 million. The equipment will be depreciated straight-line over 6 years but in fact, it can be sold after 6 years for $500,000. The firm believes that working capital at each date must be maintained at a level of 10% of next year's forecast sales. The firm estimates production costs equal to $1.50 per trap and believes that the traps can be sold for $4 each. Sales forecasts are given in the following table. The project will come to an end in 6 years when the trap becomes technologically obsolete. The firm's tax bracket is 40%, and the required rate of return on the project is 12%. Year: Sales (millions of traps) 0 0.00 0.50 5 0.60 4 1.00 6 0.20 Thereafter 0.60 1.00 a. What is project NPV? (Negative amount should be indicated by a minus sign. Do not round intermediate calculations. Enter your answer in millions rounded to 3 decimal places.) NPV million b. By how much would NPV increase if the firm uses double-declining balance depreciation with a later switch to straight-line when remaining project life is only two years? (Do not round intermediate calculations. Enter your answer in millions rounded to 3 decimal places.) The NPV increases by million