I'm trying to calculate if an item will still be in stock when used in a certain amount during the week or if I need to buy them and by how much.

Current I have this set up:

A1=18
A2=5

A1 is 18 eggs per box and A2 is the quantity used. My formula is:

=IF(A1-A2*7<=5,"BUY","IN STOCK")

The 7 is from 7 days/week. I want the "BUY" part to look something like: "BUY=1" if it's lower than A2.

Thanks if you can help.