The sum of the angles of any triangle must add up to 180°. Since we have the expressions for each angle: 5x, 8x, and (2x +9), we can solve for the variable of 'x' by adding the expressions together and setting them equal to 180:
A square has 4 equal sides, this means the 2 sides we will multiply to get the area are going to be the same. Since it says 81 yards squared and the shape is a square, we can do the square root of 81 which is 9.
