Radhika borrowed Rs 12000 from her friends. Out of which Rs 400 was borrowed at 18% interest, and the remaining for a 15% rate of interest per annum. What is the total interest and total amount she paid after 3 years?

a) Total interest: Rs 5436, Total amount: Rs 17436
b) Total interest: Rs 6160, Total amount: Rs 18160
c) Total interest: Rs 5436, Total amount: Rs 12000
d) Total interest: Rs 6160, Total amount: Rs 18200