For the first investment the solution as follows
Annual depreciation
600,000÷6 years=100,000
Net annual cash flows
100,000+155,000=255,000
Present value
255,000×4.11141+16,600×0.50663
=1,056,819.608
Net present value
1,056,819.608−600,000=456,819.608
For the second investment the solution as follows
Annual depreciation
390,000÷8 years=48,750
Net annual cash flows
48,750+60,000=108,750
Present value
108,750×4.96764+24,500×0.40388
=550,125.91
Net present value
550,125.91−390,000=160,125.91