I played each level the three times to amass enough money to upgrade everything and money leftover to start off strong on the next restaurant. As others have pointed out: you need to spend money on boosts to advance in the donut shop. Fine, I foolishly paid it and moved on to pizza, which thankfully could be finished without many and had about 30k left. Then I get on the stupid boat and THE CURRENCY CHANGED! So my 30k went poof. Can't get past level six w/o buying coins. Save your money/time.