The perimeter of an equilateral triangle is 40 cm more than the length of each of its sides. What is the length of each side of this equilateral triangle ?

20 cm

According to the question,

Let the side of the equilateral triangle = a cm

The perimeter of an equilateral triangle =  40 + a

Perimeter of equilateral triangle = sum of all sides

= 40 + a = a + a + a

= 40 + a =3 a

= 40 = 3a - a

= 2a = 40

= a = 20cm