If the price of the product is X Yuan at 80% price reduction, then the original price of the product is?

If the price of the product is X Yuan at 80% price reduction, then the original price of the product is?

Cost price is unit 1
The price is 1 + 30% = 130%
The price is 130 × 80% = 104%
So the commodity earned, earned 104-104 △ 104% = 4 (yuan)