The phrase "varies inversely" means that the value of V increases when T decreases and it decreases if otherwise. Let k be the constant of this inverse variation such that,
V = k/T
Substituting the given values,
18 = k/3
The value of k is 54. Thus, the inverse variation may be written as,
V = 54/T
Among the choices, the answer would be letter A. v = 54/T.