20 cm2. Each side of the square is 6 cm in length, so the total area is 36 cm2. The area of A is the area of the square minus the sum of the areas of the three triangles.
Three. On the first night, you’ll host nine tents and make $180, which you’ll use to upgrade three sites. On the second night you’ll host three RVs and six tents, earning $240, letting you upgrade another four sites. On the third night you’ll host seven RVs and two tents, earning you more than enough to upgrade the last two.