Sample response: Any polygon can be broken into triangles. There are two less triangles than the number of sides in the polygon. You can multiply the number of triangles formed by 180° to find the sum of the interior angles. The sum can be written as (n – 2)180, where n is the number of sides.
Well 13 /3 = 4.3333, that sure the cost for one book and the rate. so if he bought 12 books at the same rate, then its 12*4.33333. which equals 52 dollars
