To find the length of an edge
You have to know that there are 6 square surfaces on a cube.
So the equation would be 6a² because is the surface area formula and is equal to 100 square inches
Solve for the a:
6a² = 100
a² = 100/6
a= √( 100/6)
a = 4.0825 in
Rounded to the nearest tenth
a = 4 in