We had a rate card that included both the cost to the agency per hour for a particular role and the agreed rate we had settled with the client. We had a fixed rate for each role/locale even though we paid people different amounts. I knew my own salary and handful for my direct reports and the "cost" side of the rate card was a lot more than I was getting paid. And that cost was the base on which padded to get profit from the client.

And that profit itself wasn't pure profit for the company because a lot of paid for our fixed costs (office space, hardware) and non-billable roles (HR, receptionists). And of course a lot of it ends up in the hands of our holding company and their stock holders.