Let the sum be Rs. x
a. gives, S.I = Rs. 9000 and time = 9 years.
b. gives, Sum + S.I for 6 years = 2 x Sum
--> Sum = S.I for 6 years.
Now, S.I for 9 years = Rs. 9000
S.I for 1 year = Rs. 9000/9 = Rs. 1000.
S.I for 6 years = Rs. (1000 x 6)= Rs. 6000.
--> x = Rs. 6000
Thus, both a and b are necessary to answer the question.
