Solve the following modifications of the capital budgeting model in Figure 14.40.
a. Suppose that at most two of projects 1 through 5 can be selected.
b. Suppose that if investment 1 is selected, then investment 3 must also be selected.
c. Suppose that at least one of investments 6 and 7 must be selected.
d. Suppose that investment 2 can be selected only if both investments 1 and 3 are selected.