The amount of a certain sum in 3 years at simple interest at $$x \%$$ p.a. is ₹5,472 and the amount of the same sum in $$7\frac{1}{2}$$  years at the same rate, at simple interest is ₹6,930. The value of $$x$$ is:

A

7.2

B

8.5

C

8

D

6.5