Answer:
60 onions
Step-by-step explanation:
If two batches of soup serve 8 people, one batch of soup serves 4.
Divide 120 by 4 to decipher how many batches you will need for that many people, which is 30.
If you need 2 onions for one batch, multiply that many by how many batches (2 * 30 = 60)