create table Account(id int identity, F1 int, F2 int,F3 int)

insert into Account(F1,F2)
values
(20000,0),
(0,5000),
(55000,0),
(0,60000),
(0,20000),
(11000,0)

select id,F1,F2,(select SUM(F1-f2) from Account where id <=a.id) F3 from Account a