SALES RETURN MORE THAN SALES

MARCH  2020  SALES IS-   150000+13500+13500 ( SGST 9+CGST 9%)

AND SALES RETURN  IN MARCH   IS  320000+28800+28800

SO

3B SHOWING NEGATIVE BALANCE

AS      OUTWARD SUPPLY    (-170000) + (-15300)+  (-15300)

HOW TO TREAT IN 3B??

THERE IS NO NEGATIVE  ENTRY 

WHAT DOO