Kim owes Todd a sum of money for money she has borrowed. They cannot agree on the exact amount and have no record of the loans made over a long period of time. Kim doesn't have all the money to pay now, and Todd could sue her and collect the funds. Kim and Todd, however, agree for purposes of settling this debt that the sum owed is $35,000, and that Kim will pay Todd $5,000 per month until the debt is paid. What type of arrangement have they made?