Emilio Eye Enterprises purchased an electronic eye imaging machine, today, costing $100k. After 2 years they will need to spend another $20k to perform required maintenance & upgrade the software. At the end of 4 years, they will be able to sell the unit (salvage value) for $30k. If the interest rate is 10%, and n=4 years, which one below, if any, is a correct formula for finding the EUAW for the investment?

		EUAW = -$100k (A/P, 10%, 1) - $20k (A/F, 10%, 2) + $30k (A/F, 10%, 4)
		EUAW = -$100k - $20k (A/P, 10%, 2) + $30k (A/P, 10%, 4)
		EUAW = [ - $100k - $20k (P/F, 10%, 2) + $30k (P/F, 10%, 4)] [A/P, 10%, 4]
		None of the above formulas are correct