How it works
Leo wanted to know whether his Juice Cart was really earning, or only felt busy. He kept track with three words: sales, costs and profit.
Some costs stay the same, like the 4 coins a week Mr Oak charges for the cart's spot. Others come back with every cup: a lemon, sugar and a paper cup cost 1 coin.
When the coins in and the coins out are equal, the profit is zero. That is called breaking even: no gain and no loss.
Busy is not the same as profit. That is why every coin gets counted, even the costs that never change.