I would go with 75.4 square meters. Since the circle in the middle has a diameter of 5.4m and on either side of the middle circle, it’s 2.2m to the edge of the deck. 5.4 + 2.2 + 2.2 = 9.8. The diameter if the deck (one large circle) is 9.8m. To find area, we use pi*radius squared. The radius of the deck is 4.9 m. 4.9 x 4.9 is 24.01. 24.01 x Pi is approximately 75.39m squared, so rounded to 75.4m squared.
