What is the average of the real numbers a, b, c and d?
I) a + b + c = 16 + d
II) 3(b + c + d) = 20 - 3a

A

If the statement I alone is sufficient to answer the question.

B

If the statement II alone is sufficient to answer the question.

C

If both the statements I and II are sufficient to answer the question but neither statement alone is sufficient.

D

If both the statements I and II together are not sufficient to answer the question and additional data is required.