This is like 8 years late, but if anyone happens to get stuck on this problem as I did, here's a decent explanation. For this post, I will specifically talk about the following candidate 0 - x += 0. Breaks in loops can have many different functions, but for the problem, it breaks the inner loop. This sounds pretty confusing, so let me put it in layman's terms: "Breaking the inner loop basically means restarting the inner loop and moving onto the next outer loop". I will use the for loops provided by the example in the book - inner and outer. Let's say we're "walking" through the process. The first walk we take, we come out with an x - value of 3 (x = 0 + 3), and a y - value of 28 (y = 30 -2). So far, pretty easy. The second walk we take through the loop we end up with an x - value of 6 and a y-value of 26.
Now comes the tricky part. You might be tempted here and say, "Oh no! the x - value is 6 so the loop has to break now". Chill out, and wait. The if statement holding the break statement comes later. So with that in mind, let's continue. We are walking, and we have an x value of 6 still and our y - value becomes 24. Now the break statement is here. Now we can get out of this loop. You might think we're down with this cycle, but not just yet. We still have that sneaky y = y - 2 at the end. The reason we're only using it now is that it isn't the inner loop. Look at the curly braces and you'll see it's part of the outer loop. So our y -value concludes to be 22.
This break statement ends the loop. This is where it gets confusing, but I will do my best to explain. In Java, we typically count from 0; x < 3 means {0, 1, 2}. The following example we have here is called a nested loop. A really great youtuber who has a nice video for this is Alex Lee. He gives a more in-depth explanation of these loops and has some examples of them. Anyway, the way you have to read this loop is as-is: "Loop inner is performed 3 times per loop of outer". In algebraic terms, we can say x = 3x. The reason for this is because inner loops 3 times - {4, 3, 2}. However, when we have the break statement, this ends the inner loop. Forcing the outer loop to restart and perform its second loop - in this case it would be 1 due to the java counting system {0, bold(1), 2}.
So, after the break, the outer loop goes to its second stage (1), and the inner loop restarts at 4. Now we take a walk and our x - value stays at 6 as 6 + 0 = 6, and our y - value becomes 20. Now we encounter the break statement again. Like I said before, this ends the inner loop again. We now implement the y = y - 2 as the break statement breaks us from the loop allowing us to walk to this line. Our y - value now becomes 18.
Finally we are on our last loop - {0, 1 , bold(2)}. And we restart at the 4th inner loop. Again, our x - value stays at 6 and our y- value decreases by 2 giving us 16. Then we encounter the break loop, which sends us out of the loop inner, letting us to use the y = y - 2 line which makes our final y - value 14.
Here's a chart which can help you visualize what I said better:
https://prnt.sc/10171t5