On peut faire varier les tarifs “a” (tarif journalier pour un petit espace) 
et “b” (tarif journalier pour un grand espace) tout en gardant a < b 

a_1(x, y) = x + y ≤ 138
b_1(x, y) = (10 * x) + (30 * y) ≤ 3000
f: x + y = 138
g: (10 * x) + (30 * y) = 3000
h: x = 0
i: y = 0
A = Intersect(g, h)
B = Intersect(f, g)
C = Intersect(f, i)
a = 20 (slider from 20 to 35, step 0.05)
b = 30 (slider from 30 to 45, step 0.05)
Z(x, y) = (a * x) + (b * y)
Z_A: (a * x(A)) + (b * y(A))
Z_B: (a * x(B)) + (b * y(B))
Z_C: (a * x(C)) + (b * y(C))
D = Intersect(h, i)
poly1, a_2, b_2, c, d = Polygon(A, B, C, D)