3a, b and c please help

3. (30pt) A company considers the following 4 projects: Project Capital Investment in year 0$10,000$6,000 A D $4,000 $8,000 -$2,000 $5,000 $1,600 $1,300$1,500 $4,000 $5,000 $8,000 $1,200 Net Cash Flow in 1 year Net Cash Flow in year 2 $4,000 $8,000 $10,200 Net Cash Flow in year The MARR is 10% per year. The company has a $20,000 budget for the capital investment in year 0. a) (10pt) Find NPV8 of 4 Projects, formulate a binary integer programming problem to select projects that maximizes the total NPV, and determine which projects the company should se- lect by solving the problem with the Excel solver b) (10pt) In addition to the budget constraint, we further assume that the total cash flow in year 1 must be nonnegative. Formulate a binary integer programming problem to select projects that maximizes the total NPV, and determine which projects the company should select by solving the problem with the Excel solver c) (10pt) In addition to the constraints in b), we further assume that Project C can be chosen only if Project D has been selected and that Projects B and C are mutually exclusive. Formulate a binary integer programming problem to select projects that maximizes the total NPV, and determine which projects the company should select by solving the problem with the Excel solver