For the system of inequalities x−y≥2, y≥1, x≥0, consider the expression S=4x+y to be maximised.
a. (i) Draw the feasible region determined by the constraints.
b. (ii) Determine whether S attains a finite maximum value in the feasible region. Give a clear justification based on your graph.
c. (iii) Find the minimum value of S, if it exists, and the corresponding point.