unir resultado de dos tablas

[mikil]

ya està!!!!!!
y aquí queda para quien lo necesesite

Código:

select tda, familia, sum(numvta) from 
    (select  tda as tda, left(montura,1) as familia , count(*) as numvta from regicaja
     inner join monturas on montura = monturas.moncodi
     where fecven>='2012-05-02' and fecven<='2012-07-15' and monturas.monrelacio = "3600"
     group by tda, familia
     union all
     select vtatda as tda, left(vtamontura,1) as familia, count(*) as numvta from vendes
     inner join monturas
     on vtamontura = monturas.moncodi
     where vtafecven>='2012-05-02' and vtafecven<='2012-07-15' and monturas.monrelacio = "3600"
     group by tda, familia) as resultat

group by resultat.tda, resultat.familia