A commodity is priced at 20% profit and then sold at 20% discount. As a result, it loses 40 yuan. How much is the cost of this commodity?

A commodity is priced at 20% profit and then sold at 20% discount. As a result, it loses 40 yuan. How much is the cost of this commodity?

Set the cost as C:
Price before discount = C (1 + 20%)
Price after discount = C (1 + 20%) × 80%
Plus a loss of 40
So cost C = C (1 + 20%) × 80% + 40%
C=1000