Answer:
4
Explanation:
Let's think of this as a cube with layers.
(Layer = height)
If the first layer has 20, and the cube has a total of 80, we can use this equation:
80 = 20 × number of layers
Let's figure out how many times we need to multiply 20 to get 80.
20 × 4 = 80
The cubes height is 4.