Atriangular prism has an equilateral base with side length x inches. the height of the prism is four times as long as the side length. what is the lateral area of the prism?

Let
x> side length of the equilateral triangle
y> the height of the prism

we know that
y=4*x
[lateral area]=perimeter of the base*height
perimeter of the base=x+x+x>3*x
[lateral area]=3*x*y> 3*x*[4*x]> 12*x² in²

the answer is
the lateral area is 12*x² in²