Complex sentence: The selection made (projects 1,3,6 and 7, total investment: $7,740,000) is the optimum under these conditions, all other combinations of projects would either exceed the budget or yield a lower payoff.
Split into simpler sentences: The selection made (projects 1,3,6 and 7, total investment: $7,740,000) is the optimum under these conditions. All other combinations of projects would either exceed the budget or yield a lower payoff.