frustum of a cone

The frustum of a cone shown is formed by passing a plane parallel to the base of a right circular cone, then turning the small right circular cone upside down. Given that the height of the original right circular cone is twice its radius and the height of the passing plane is three fourths the height of the original right circular cone, find the ratio of the volume between the frustum and the small right circular cone to the volume of the original right circular cone. If your answer can be expressed as $\dfrac{x}{y}$ where $x$ and $y$ are positive coprime integers, give $x+y$ .