I agree with Hugo that the information you provided is not sufficient to
give you a good answer. Here is just a guess based on your explanation and
expected results:

SELECT C.cerveh, C.monto1, A.prima
FROM Arysauto AS A
JOIN (SELECT ramo, cerveh, poliza, stcdcb,
SUM(monto1) AS monto1
FROM Clpf08
GROUP BY ramo, cerveh, poliza, stcdcb) AS C
ON A.cerveh = C.cerveh
WHERE C.ramo = 31
AND C.poliza = 6100265
AND C.stcdcb = ' '
AND EXISTS (SELECT *
FROM Clpf07 AS B
WHERE B.ramo = C.ramo
AND B.poliza = C.poliza
AND B.cerveh = C.cerveh
AND B.actret <> 'R')
AND C.monto1 - A.prima > 0;

HTH,

Plamen Ratchev
http://www.SQLStudio.com