PLEASE HELP THIS IS URGENT

Answer:
[tex]\large\boxed{A_\triangle=\dfrac{5}{6}x^2}[/tex]
Step-by-step explanation:
The formula of an area of a triangle:
[tex]A_\triangle=\dfrac{bh}{2}[/tex]
b - base
h - height
We have
[tex]b=\dfrac{5}{3}x,\ h=x[/tex]
Substitute:
[tex]A_\triangle=\dfrac{\left(\frac{5}{3}x\right)(x)}{2}=\left(\dfrac{5}{3}x^2\right)\left(\dfrac{1}{2}\right)=\dfrac{5}{6}x^2[/tex]