Answer:
32 Liters
Step-by-step explanation:
In the glass tank:
W = represents the volume of water Andrei uses (in liters)
n =Number of marbles
Given that: 
The volume of the glass tank is the volume of the water in the tank plus the total volume of n marbles added.
Therefore:

Volume of the tank =32 Liters
Answer:
20 by 20
Step-by-step explanation:
the new dimensions have to be 12 because 12×12 =144 so you would add 8 to 12 and get 20 for each side
The unit rate is 2 pens/1 notebook