Find the ratio of: The the lateral area of the smaller cone to the lateral are of the frustum

Question

A cone is cut by a plane parallel to the base, 1/ 5 of the way up the height of the cone (from the base), resulting in a smaller cone and a frustum. Find the ratio of: The the lateral area of the smaller cone to the lateral are of the frustum

Answer 1

Here's the formula: SA = πr² + πrl (L=side"c").