Tip:
To address the stipulation that that at least two of the projects 1, 3, 5, 6 must be undertaken, make Sum of B12, D12, F12, G12 >= 2

To address the stipulation that Project 4 cannot be undertaken unless both projects 1 & 3 are also undertaken make E12<= B12 & E12<=D12

Model

Brooks Development
Parameters
Project 1 2 3 4 5 6
Net Present Value ($ Millions) $15 $5 $13 $14 $20 $9 Budget
Expenditure Required ($ Millions) $90 $34 $81 $70 $114 $50 $220
Model
Project 1 2 3 4 5 6
Invest
Cost $0.00
Total NPV $0.00
Projects 1,3,5,6