中一數學問題(百份數)

Let y be the marked price.
45%y=27
y=60
Therefore the marked each pen is$5.
So the selling price is:
=(5*12-27)/12
=33/12
=$2.75
Hope that I can help you!!給最佳我吧!! Thanks a lot!!

Let $y be the selling price of each pen.
12y x (1-45%) = 12y - 27
12y x 0.55 = 12y - 27
6.6y = 12y -27
5.4y=27
y=5
∴The selling price of each pen is $5

let x be the original selling price
x(45%)=27
x=$60

the new selling price
=60(1-45%)
=$33

selling price of each pen
=33/12
=$2.75

答案冇可能係2.75，係5
因為45%x=27(設x係12支筆的價錢)
因此27/45%=x
x=60元(12支筆)
再計每支的價錢，即60/12=5
所以應該係每支5元