數學題唔識(急用)

(a)
$600÷(1+20%)
=$500

(b)new selling price
$600X(1-55%)
=$270

her loss percent
($500-$270)÷500X100%
=46%

a)let c be the cost price.
c(1+20%)=$600
c=$600/1.2
=$500
b)after decrease the celling price by55%,the selling price should be:
$600(1-55%)=$270
we konw that the cost price is $500,
so,her loss percent=($270-$500/$500)x100%
=(-$230/$500)x100%
=-46%
so,it loss46%

Mary sells an electric kettle at $600 and the profit percent is 20%.
(a)Find the cost price of the electric kettle.
let x be the cost price of the electric kettle,
(1+20%)x = $600
1.2x = $600
x = $500//
the cost price of the electric kettle is $500.

(b)lf she decreases the selling price by 55%, find her loss percent.
the new selling price after decreasing by 55%,
600 x 55%
= $330

the loss percentage,
　　 330
1-　 -----　 x 100%
　500

= 34%

2007-03-09 18:11:37 補充：
(b)lf she decreases the selling price by 55%, find her loss percent.//sorry i read the question wrong//the new selling price after decreasing by 55%,600 x 45%= $270the lost percentage,1 - (270/500 x 100% )= 46%

(a)
20%=(600-cost price)/cost price
0.2cost price=600-cost price
1.2cost price=600
cost price=500
The cost price of electric kettle is 600 dollars
(b)
After she decreases the selling price by 55%, the selling price is
600x45%
=330
So, her loss percent is
(500-270)/500x100%
=46%