How do you get the Cost of Goods Sold for a condensed income statement?

I can't seem to understand it.

Very simple concept.

You start with the OPENING BALANCE of STOCK, you add the PURCHASES and you subtract
The CLOSING BALANCE of STOCK.

Very simple concept.

You start with the OPENING BALANCE of STOCK, you add the PURCHASES and you subtract
the CLOSING BALANCE of STOCK.

Thanks so much!