Task: Question Answering
Input (English): Problem: an equilateral triangle t 2 is formed by joining the mid points of the sides of another equilateral triangle t 1 . a third equilateral triangle t 3 is formed by joining the mid - points of t 2 and this process is continued indefinitely . if each side of t 1 is 40 cm , find the sum of the perimeters of all the triangles . 
Options: ['a ) 180 cm', 'b ) 220 cm', 'c ) 240 cm', 'd ) 270 cm', 'e ) 300 cm']
Output (English): c