A sum of ₹ 12,800 is invested partly at 15% per annum and the remaining at 12% per annum simple interest. If the total interest at the end of 3 years is ₹ 5,085. then how much money was invested at 15% per annum?

A

₹ 5,300

B

₹ 7,500

C

₹ 5,800

D

₹ 5,200