SQL & PL/SQL :: Compare 2 Tables Based On 2 Columns

My tables looks like this:

Desc Table A (account)
Account1_id
Account2_id
name,
empid

Table B (Bill )
BillNo
Advertiserid
agencyid
total vvalue

I need to pick up total value from table B where the unique combination of advertiser-Agency id is the same as the given account1_id -Account2_id combination in table A for each employee id.

In other words my output should be like

Empid | Account_id (should be same as advertiserid)| Account2_id (same as agencyid) | sum(total_value) for this adv-agency combination.....

objective: Get the total value from table B for each unique account1-account2 combination (advertiser-agency in other words) .

I am not sure if I should use a correlated subquery or how to handle the situation....Right now I am just checking the two columns separately like this:

select.......from a,b
where b.advertiser_id = a.account1_id and b.agencyid = b.account2id

Is it correct to do so? I have a feeling that I am missing something if I join them separately like this.