The secret to repaying debts quickly and saving on interest charges is to continue to pay the same amount each month until all debts are repaid. As one debt is paid off, apply that payment amount to another debt.
To move forward with the same example, the current monthly payment is $850. If you pay an additional $180 each month that’s mean $1030 of total monthly payment, your debts will be repaid in 7 years and 10 months and you will avoid $23.617 in interest charges.
As you noticed, by simply allocating $180 you save $23.617 meaning if you allocate more monthly payment you will save more and more!
If you follow your Debt Free/Reduction Plan, you will save $23,617.86 in interest which is equivalent to 39.5% and have your debts paid off in 7 years and 10 months and not 13 years and 2 months.