SQL & PL/SQL

hi, i am using oracle 10g database..

how to get the sum of column in union query ?

     select * from (select 100 records from dual), (select 50 available from dual)
union
select * from (select 200 records from dual), (select 150 available from dual)


display should be like 

                 records         available
                  100               50
                  200               150
 total            300               200

thanks ...