= -35,019.37 currency units. Under the named conditions, you must deposit 35,019.37 currency units today, if you want to receive 500 currency units per month for 48 months and have 20,000 currency units left over at the end. Cross-checking shows that 48 x 500 currency units + 20,000 currency units = 44,000 currency units.
= -35,019.37 个货币单位。也就是说，要想在 48 个月期间每月获得 500 个货币单位且在完成最后一次支付后的剩余金额为 20,000 个货币单位，那么您目前必须投资 35,019.37 个货币单位。通过一个对比计算：48 x 500 个货币单位 + 20,000 个货币单位 = 44,000 个货币单位，您可以见到计算结果 44,000 个货币单位与投资金额 35,019.37 个货币单位的差额是您获得的利息。