Sketch the feasible regions defined by the following sets of inequalities:

(a) 5x + 3y ≤ 30

7x + 2y ≤ 28

x ≥ 0 

y ≥ 0

(b) 2x + 5y ≤ 20 

x − y ≤ 4

x ≥ 0

y ≥ 0

(c) x − 2y ≤ 3
x + y ≤ 5
x ≥ 1
y ≥ 0