Which steps could be used to solve this story problem?

billy had 20 rubber balls and 12 plastic balls. he shared the balls equally among 4 friends.

how many more rubber balls did each friend get than plastic balls?

a.
subtract 12 from 16. then multiply the difference by 4.

b.
divide 20 by 4. divide 12 by 4. then find the difference between the two quotients.

c.
multiply 20 by 4. multiply 12 by 4. then find the difference between the two products.

d.
subtract 4 from 20. subtract 4 from 12. then add the differences together.