I need fms at line level rows(substring)

hi.

i need small  information.

plz have a look on below image.

SELECT  QTY= ($[$38.21.0])

FROM   OSTC  WHERE  OSTC.Code ='TEST'

i just put the above fms at row levle udf at sales order.

when ever i run the query  the value is comming like

INR 500.00

BUT I NEED ONLY  500.00

HOW CAN I GET ONLY  500.00

i need your valuable suggestions..