Get rows whose sum matches a value

This should be simple, but I can't work it out without cursors.

 I have a table with quantity field. I want to get all first rows
whose sum of quantity matches defined value.

No    Quantity
=============
1       50
2       50
3       80
4       80
5       80
6       50

If defined value is, lets say, 180, query should return rows 1..3
Something like
select *
from table
where sum(quantity) = 180
order by No

Any way to work this out?

Thanks,

Mario B.