I dont quite get this..

Question

Answer 1

Calculate the interior angle by using the formula : [180^o(n - 2)] / n, where n is number of sides.

From the figure, interior angle is 108^o.

180^o(n - 2)  / n = 108^o

(n - 2)  / n = 108^o/180^o

(n - 2)  / n = 3/5

5(n - 2) = 3n

5n - 10 = 3n

2n = 10

n = 5.

The second option is correct answer.