Grogg stacks three identical cubes to create a rectangular prism with surface area of $84$ square inches. what is the surface area, in square inches, of one of groggs cubes

Alrighty

3 cubes
if you stack them then you can cover, at most 3 faces

each cube has 6 faces
so 6*3=18
minus the 3 coverd is 18-3=15

so if the surfece area is equal to 15 of those faces ten
84=15 faces
divide by 15
84/15=area of 1 face

a cube has 6 faces to multiply by 6
84/15 times 6=504/15=168/5=33.6 square inches is the surface area of one of grogg's cubes