1) There are two ways of getting one blue and one red, each of which has the same probability:

B-R
R-B

Since the total probability is 1/4, P(B-R)=1/8 and P(R-B)=1/8. If we have 7 red and 1 blue, then P(R-B) = 7/8 * 1/7 = 7/56 = 1/8. P(B-R) would have the same probability for a total of 1/4. However, we can also arrive at the same probability if we have 7 blue and 1 red. Insufficient.

2) R + B = 8. There are many possible combinations of red and blue marbles. 1 and 7, 2 and 6, and so on. Insufficient.

When put together, we still have the same possibilities we had in Statement 1, so we still cannot answer.