Zion made a triangular-shaped house of cards with the base having a measurement of 40 centimeters and a height of 20 centimeters. If two of his friends also built similar shaped houses, what's the total area of the triangular houses that Zion and his friends made (the area of a triangle is 1/2 * width * height)?
Since the area of a triangle is given by 1/2 base*height, the area of the triangular-shaped house of cards that Zion made is 1/2*40*20 = <<1/2*40*20=400>>400 square centimeters.
If two of his friend also built similar shaped houses, the total area of their triangular-shaped house of cards is 400+400=<<400+400=800>>800 square centimeters.
Together with Zion, they all built triangular-shaped houses of cards with a combined area of 800+400=<<800+400=1200>>1200 square centimeters.
#### 1200