What is the minimum amount of cloth that was used to make the tent shown below?

From the figure, we can identify 5 surfaces.

There are 4 identical triangular surfaces,. Each triangle has a base of 230 m, and a height of 187 m.
The area of one triangle is
A₁ = (1/2)*230*187 = 21505 m²

There is one square surface. Each side is 230m.
Its area is
A₂ = 230*230 = 52900 m²

The total surface area is
A = 4*A₁ + A₂
    = 4*21505 + 52900
    = 138,920 m²

138,920 m²