Three lots with parallel side boundaries extend from the avenue to the boulevard as shown answer

Three lots with parallel side boundaries extend from the avenue to the boulevard as shown in the diagram attached.

Given;
            x + y + z = 140 meters

According to the proportion theorem,



Solving for x, using cross multiplication:



Similarly,

x/40 = z/35

solving for z by cross multiplication,

z = 35x/40
z = 7x/8

Now, the third proportions,
y/30 = z/35

Solving for y,

y = 30z/35
y = 6z/7

x + y + z = 140

 4y/3 + 6z/7 +  7x/8 = 140

(224y + 144z + 147x)/168 = 140

224y + 144z + 147x = 23520

Substitutoing z = 7x/8,

224y + (144 × 7x/8) + 147x = 23520

224y + 126x + 147x = 23520

224y + 273x = 23520
Now,
Substitute y = 3x/4

(224×3x/4) + 273x = 23520

168x + 273x = 23520

441x = 23520

x = 53.33

Now,
We know that
y = 3x/4
so,
y = 40

And,
z = 7x/8
Z = 46.66

Spherical shaped cell might increase the surface area and decrease the volume.