a. The model with slack variables.
b. The meaning of the entries in rows 1 and 2.
Row 1 indicates that constraint E1 is loose and changing its
right side will not affect the objective function.
Row 2 indicates that increasing the right side of E2 by 1 will
increase the objective function by 0.75.
c. The figure shows the original objective function lines and
the lines at the limits of the range. The solution remains optimal
in the range.
d. When the right side of E3 increase to 16, only one point
is feasible and must be optimal. For any further increase there
can be no feasible solution.