3 cans of soup can serve 5 people.

If you want to serve 20

people, what should you do?

Use 15

more cans of soup.

Use 4

times as many cans of soup.

Use 3

times as many cans of soup.

Use 12

more cans of soup.

Use 12 more cans of soup.

To serve 20 people, you would need to use 4 times as many cans of soup. Thus, you would need to use 3 cans of soup x 4 = 12 cans of soup. Therefore, the correct answer is to use 12 more cans of soup.