Divide the nonagon radially into 9 congruent, equilateral isosceles triangle. Each triangle has vertex angle of 360°/9 = 40°.
Interior angle of polygon = 180°-40° = 140°.
Sum of interior angles = 9(140°) = 1260°
The answer is on the paper
The expression that is equivalent to 3t + 3t is 6t
