Answer:
The answer to your question is 9 cups of milk
Explanation:
Data
20 pancakes/3/2 cups of milk
120 pancakes/? cups of milk
Process
Use proportions to solve this problem
 20 pancakes ----------- 3/2 cups of milk
 120 pancakes ---------- x cups of milk
 x = (120 x 3/2) / 20
Simplification
 x = (360/2) / 20 
 x = 180 / 20
Result
 x = 9 cups of milk