You are going to take a loan of $100,000 from a local microfinance institute to repay in 12 equal installments. The institute deducts 10% as a fixed deposit at the time when you take the loan. Your installment per month is $10,155. How much interest are you paying? [Hint: calculate the interest rate per period and multiply it by 12]

(I must solve the problem on paper with a formula, not on Excel) Thank you!