修复账单缴费余额与结算余额错误

application/em/model/EmInvoice.php

@@ -53,7 +53,7 @@ class EmInvoice extends Base
 //                 $item['sett_amount'] = number_format($item['settle_amount']) - number_format($item['settle_balance']);
 //             }
 //        }
-        echo 123123.12312-123100.34534;
+        echo '123123.12312'-'123100.34534';
         die;
         return $data;
     }