Maths .

咁你搵番個原價先啦...
設原價係y..
y(1-5%)=285
95%(y)=285
y=285/0.95
y=$300
so原價係$300

increases the selling price by 20%
285x(1+20%)
=285x1.2
=$342

his profit per cent is:
(342-300)/300x100%
=42/300x100%
=0.14x100%
=14%

If a man sells a chair at $285 , then the loss per cent is 5%. Find his profit percentage if he increases the selling price by 20% .

ANS :
Let the cost of the chair be $P
P x (1-5%)=285
P x 95%=285
P=285/0.95
P=300
Therefore,the cost of the chair=$300

The selling price
=285 x (1+20%)
=$342



The profit percentage
=(342-300)/300 x 100%
=0.14x100%
=14%

希望幫到你la~~@_@

2007-11-15 21:12:20 補充：
YOUR ANSWER ( 14% ) is correct ~!