The repayment amount is 1207,92 USD, because the loan principal is 1200 USD and the interest is 7,92 USD (1200 x 0,033% x 20). Hence, if you repay the loan in BTC, you will refund 0.11614615 BTC (1207,92 / 10400) which is 0,03385383 BTC less than you initially borrowed.