A shopkeeper mixes two qualities of rice, which cost him ₹40 per kg and ₹47.50 per kg respectively, in such a way that he has 15 kg of the blended rice costing him a total of ₹645. What is the weight (in kg) of the rice that cost him ₹47.50 per kg?

A

5

B

6

C

10

D

9