The area of a trapezoid is equal to 1/2 times the 2 bases added together (bases of a trapezoid are parallel, and in this case it looks like it's 2m and 2.5m) times the height of the trapezoid (perpendicular to the opposite side, and forms a right angle).
So the equation would be 1/2 (2 + 2.5) times 6, which is 13.5 meters squared.