I run a bakery and sell two sizes of loaf. Small loaves (weighing 240 g) sell for 80p, and large loaves (weighing 400 g) sell for £1.20. I buy dough, ready-made, at the start of each day. Small boxes (5 kg of dough) cost me £10.00 each, and large boxes (15 kg of dough) cost me £20.00 each. The baking process causes each loaf to lose 20% of the weight of the unbaked dough. I expect to sell 40 small loaves and 50 large loaves each day. I buy enough dough to be able to make these, and any unused dough at the end of the day has to be thrown away.