Yes. I understand it. It's similar to many other force/pressure exercises that I've seen in the past, and I've even been known to solve some of them.
Perhaps you're stressed over this exercise because you're being distracted by other things that you've got going on at the same time. You really ought to close the email (2), supermarket, and student chart tabs that are open in the background, and focus your full attention on your homework for a while. Give your natural cunning intelligence and smarts a chance to totally burn into the homework problem and demolish it.