If Purchases is 100000, Sales is 90000, margin is 20% on cost. What is the closing stock?

If Purchases is 100000, Sales is 90000, margin is 20% on cost. What is the closing stock?

Not enough info.

If margin is 20% on cost, then the sales price must be equal to 100 + 20 = 120. Based on this the cost of sales will be 90000/1.20 = 75000, and if there is no opening inventory the closing inventory will be 100000 - 75000 =25000.

Based on the assumption there was no beginning inventory. (Unless I can tell something has been copied verbatim, I never quite trust that's really all there is.)