Tip: To address the stipulation that that at least two of the projects 1, 3, 5,

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