點計cost price

下...要睇你有d 咩資料...
如果你有selling price 同 profit % 就...
selling price/(1+ profit%)
例如:selling price = $60....profit% = 20%
60/(1+20%)
60/120%
=$50

希望幫到你la =)

If it's a profit: marked price/(1+profit percent)=cost price
If it's a loss: marked price/ (1-loss percent)=cost price