Question

If beginning inventory (bi purchases (p - ending inventory (ei = cost of goods sold (cogs, an equivalent equation can be written as?

Answer 1

I had to look for the options and here is my answer:
Based on the one presented above, we can say that the equivalent equation can be written like this: BI + P = COGS + EI. BI refers to the beginning inventory and P is the purchases. The COGS is the cost of goods sold. EI is the ending inventory. Hope this helps.

Answer 2

There seems to be a missing variable here which is the total purchases. We can have an equivalent equation written as:
the cost of goods sold(cogs) = beginning inventory  + total purchases- ending inventory
where 
ei= cost of goods sold
bi= beginning inventory
p =ending inventory
t= total purchases
ei= bi+t-p
The equivalent equation is ei= bi+t-p.