(a) Find the new optimal tableau for the winery problem if the constraint constant vector is perturbed by a vector \(\Delta \mathbf{b}\) whose components are: \(\Delta_{1}=-75, \Delta_{2}=4, \Delta_{3}=16\), and \(\Delta_{4}=91 / 2\).

(b) For fixed \(\Delta_{1}=-75, \Delta_{4}=-21 / 2\), graph the set of all \(\left(\Delta_{2}, \Delta_{3}\right)\) in the plane such that the current optimal solution remains unchanged.