Query with "Logical operator (AND)" that does not return the desired result set
As Mustaccio mentioned in the comments, you want rows where dev_type is either 'x1' or 'x2', not where it's 'x1' and 'x2'.
Also you only need the brackets around each of the alternative sets of conditions. The others aren't doing anything and they are just confusing.
with test_table (customer_num, dep_group, dep_type, balance) as
     ( select 1, 'x', 'x1', 10 from dual union all
       select 1, 'x', 'x2', 10 from dual
     )
select *
from  test_table
where (dep_group = 'x' and dep_type = 'x1' and balance &gt; 1)
or    (dep_group = 'x' and dep_type = 'x2' and balance &gt; 1)