3. The Project incomes, the beginning of the period and end of the period values ($ 000) are in the following table. WACC (discount rate) is 12% and alternative return is 15%. Compute the cash flow to determine the optimum renewal period.

Periods	Project incomes En	The beginning of the period R(n-1)	end of the period Rn
1	1,200	2,400	2,100
2	1,530	2,100	1,800
3	840	1,800	1,200
4	660	1,200	600
5	420	600	0