to #1: Let a denote the length of the edge of the smaller cube then the surface area of this cube is

and it's volume is

Let b denote the length of the edge of the larger cube then the area of one face is

Then the volume of the larger cube is

Calculate the ration

to #2: Let a, b and c denote the edges of the solid. Then the volume is calculated by

If you increase the edge a of a solid by 5% then you get

Calculate the lenghtes of the 3 edges and determine the new volume. Compare this value with the initial volume.