Explanation:
So working from the bottom
The last line for x > 20 shows 13 because of the top graph, the last line is 13 and there is nothing below it.
Now for x > 16, we go up a line and see 14
That's where you would add 14 + any number below it
14 + 13 = 27. So for x > 16, you'd write 27
Going up, we have X > 12. Same thing, we go up a line and see 19. So now we just add 29 and any number below that
19 + 14 + 13 = 46. So for x > 12, you'd write 46.
You'll do that for the rest of the table. hope that helps