Try putting the coronets (0,10) on the chart.
I got that by trying to figure out how they got $19 on week three, and I estimated that on week zero he had $10 to start out with.
So I tried 10 + 3 = $13 for week day one, 13 + 3 = $16 for week two, and 16 + 3 = $19 for week three. Which means I was correct in assuming that Juan had $10 to start out with.
(I'm sorry if my explanation wasn't clear enough, I'm very not good at math or explaining things, but I'm sure that this answer is correct... My 'strategy' to get said answer probably won't work well with other questions, though.)