You use 3 cans of soup to serve 5 people. if you want to serve 20 people, what should you do?
a) use 15 more cans of soup
b) use 4 times many cans of soup
c) use 3 times many cans of soup
d) use 12 cans of soup
you : )

If there are 5 people, they get 3 cans.
We want to give the same amount of soup to everyone, so if there are twice as many people, we're going to need twice as much soup.
(10 people, 6 cans)
Now say we had 20 people. (4 times as many)
We'd use 4 times as many cans soup, which would be 3×4 = 12 cans.
So it seems tht both B and D are correct.