Problem $4-19$ Calculating Number of Periods

One of your customers is delinquent on his accounts payable balance. You$$ve mutually agreed to a repayment schedule of $$500$ per month. You will charge $1\mathrm{.}40$ percent per month interest on the overdue balance.

If the current balance is $$13,000,$ how long will it take for the account to be paid off? $($Do not round intermediate calculations and round your answer to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$