The combined inventory expression is:

The combined inventory of both stores can be obtained by simply adding the polynomials representing their individual inventories. Here's how:
Combined Inventory = Inventory of Store A + Inventory of Store B
Substituting the given polynomials:
Combined Inventory =

Now, combine like terms:

-r - 7r = -8r
7 - 19 = -12
Therefore, the combined inventory expression is:
