Hi mynery! Yes the way it works is there is one stream of computation that adds $84/s to your total money, but then there is another, separate stream of computation that subtracts $75 every second. I can see how that is confusing!
What would be happening is your money should be rapidly increasing, and then every second, $75 is subtracted. If you're seeing that your money per second is higher than $75 and yet your total money continues to decrease, let me know!