Here is what the numbers in the tableau mean:
1. The Roman Numerals name the rows. The regular numerals on top name the columns. Thus, cell III4 contains small number 2.
2. The little numbers in the upper right corner of each cell are the unit cost Sterling pays to deliver the milk from the plant to the shop.
3. The larger numbers bottom and right margins are the subtotals of both what the plants can provide (Supply) and what the shops need (demand). These are also called Rim Conditions.
4. The grand total is in the lower right cell. The numbers in the rim conditions, either vertical or horizontal, add up to the grand total.