Help? Step by step pls?

Answer:
The depth of the orange juice is 4 cm now.
Step-by-step explanation:
Volume of a Rectangular Prism or Cuboid
A rectangular prism (cuboid, or a box as we commonly call it) with a width W, length L, and height H has a volume of:
[tex]V = WLH[/tex]
Note WL is the area of the base Ab=WL, thus:
[tex]V = A_bH[/tex]
Jane has a carton of orange juice of dimensions:
W=6 cm
L = 10 cm
H = 20 cm
It's actually filled with h=8 cm of orange juice, thus the volume of juice is:
[tex]V_j=6*10*8=480\ cm^3[/tex]
When Jane turns the carton over the shaded face (the one with a base of 6 cm by 20 cm), the volume of juice is, of course, the same, but the new height can be calculated by finding the new area of the base:
[tex]A_b=6*20=120\ cm^2[/tex]
The volume of the juice when turned over is:
[tex]V_j=A_b.H'[/tex]
Where H' is the required height. Solving for H':
[tex]\displaystyle H'=\frac{V}{A_b} =\frac{480}{120}=4\ cm[/tex]
The depth of the orange juice is 4 cm now.