Respuesta :
notice, it has a square base, so the base or bottom of the rectangular prism, is a square, that means, length = width = x, length and width both have the same value, let's say "x", check the picture below

notice, it has a square base, so the base or bottom of the rectangular prism, is a square, that means, length = width = x, length and width both have the same value, let's say "x", check the picture below