#### Answer

$A=\dfrac{x^2 \sqrt 3}{36}$

#### Work Step by Step

To calculate the area the formula is given as follows: $A=\dfrac{\sqrt 3}{4}s^2$
Length of the side of the triangle is $s=\dfrac{x}{3}$
Now,
$A=\dfrac{\sqrt 3}{4}s^2=\dfrac{\sqrt 3}{4}(\dfrac{x}{3})^2$
This gives:
$A=\dfrac{\sqrt 3}{4}(\dfrac{x^2}{9})=\dfrac{x^2 \sqrt 3}{36}$