It would be a lot easier is you would provide ddl and sample data in a consumable format. Also, you should try to avoid reserved words for object/column names (all three of your column names are reserved words).

Assuming that hours is always a positive value you can just sum the values like this.

create table #SomeTable

(

CaseNum char(3),

MyHours int,

MyType int

)

insert #SomeTable

select 'xxx', 3, 1 union all

select 'xxx', 3, 2 union all

select 'xxx', 4, 1 union all

select 'xxx', 1, 1

select SUM(Case when MyType = 2 then -1 * MyHours else MyHours end) as TotalHours

from #SomeTable