declare @s varchar(100) = '1 2 5 22 4 6 -1 -5 -7 6 18 16 -9 2 5 -8 6 9 3 -7';
declare @t int = 15;

with i as
(
   select cast(left(@s,charindex(' ',@s+' ')-1) as int) x,
          stuff(@s,1,charindex(' ',@s+' '),'') as s
   union all
   select cast(left(s,charindex(' ',s+' ')-1) as int) x,
          stuff(s,1,charindex(' ',s+' '),'') as s
   from i
   where s <> ''
)
,z as
(
   select x,rank() over(order by x) r
   from i
)
select distinct a.x, b.x
from z a, z b
where a.x+b.x = @t
  and a.r<b.r