WITH t AS
(
SELECT 1 rn, 3.0 v FROM dual
UNION ALL SELECT 2,  4.5 FROM dual
UNION ALL SELECT 3,  6.0 FROM dual
UNION ALL SELECT 4, 11.0 FROM dual
UNION ALL SELECT 5,  3.0 FROM dual
)
SELECT x, rn, v
     , CASE WHEN s     < x THEN v
            WHEN s - v < x THEN x - s + v
            ELSE 0 END use_v
     , CASE WHEN s     < x THEN 0
            WHEN s - v < x THEN s - x
            ELSE v END rem_v
  FROM (SELECT 11 x
             , rn
             , v
             , SUM(v) OVER(ORDER BY rn) s
          FROM t
        )
;