Mathematical percentage: what is the cost price of a commodity with a loss of 2000 yuan and a loss of 20%? 20% of the cost of a commodity in 900 yuan is urgent.
1.
Suppose the cost price is X.
So: x-20%x=2000
Solution: x=2500
2.
Suppose the cost price is X.
So: x+20%x=900
Solution: x=750