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