The first cube has a surface area of 216 square cm. To find the second cube's edge you can think of it this way:
A cube is a figure that has 6 sides with each edge of equal length. The surface area was given. Divide the entire surface area by 6 to get the area of 1 side of the cube. 216 / 6 = 36
Then you take one side of the cube and take the square root of it because the surface area equals one edge of the cube multiplied by itself, or squared. The square root of 36 is 6.
The second cube's edge is 3 times as long. 6 is the edge of cube 1. Therefore you can take 6 x 3 =18 The second cube's edge is 18 cm.
To get the entire surface area you do the process to get the edge, but in reverse. The first step would be to square 18 to get the surface area of one side of the cube. 18 squared (or 18 x 18) = 324 squared cm
You then multiply the surface area by 6, to get the entire surface area. 324 x 6 = 1944 squared cm.
To find how much greater you can divide the second cube by the first cube's surface area. 1944 / 216 = 9
This means that the second cube's surface area is 9 times the amount of the first cube's.
I hope this helps! Thank you for using studypool I hope I can help in the future!