Hi Juan,

Thanks for using the forums to ask a question!

We go through a very similar scenario in the last video of this unit, showing step-by-step how to calculate this (the numbers given in the scenario are different, but the procedure is the same).

Please re-watch that video and let me know if there’s a point at which you don’t understand something (you could tell me the time stamp). I can help you better if I know exactly where you start to have difficulty following it.