If we are to calculate only based on his monthly payments, then we can multiply $99.50 to 48 months (4 years). This will give us a result of $4,776 as the total amount paid. However, if we are going to consider the loan amount of $3,600 plus 16% APR for a period of 4 years we can expect a total amount of $5,904 to be paid in 4 years. This is calculated based from the loan amount multiplied by 0.16 (16%) or $3,600 x 0.16 = $576 then multiplied again to 4 years plus the original loan amount.