中５溫ｆ３既數學．．唔識做．．幫幫手

第一題唔識= =||

２.)某人以$60000買入貨品A名貨品B,他將兩件貨品售出,售賣貨品A獲利18%,但售賣貨品B則虧蝕10%,而兩件貨品的總盈利為$3800,求貨品A和貨品B的成本。
設a貨品成本x
" b " " " " y

x+y=60000..........(1)
x*118%-y*90%=3800...(2)

把x代入y
x+y=60000
y=60000-x....(3)

把(3)代入(2)
x*118%-y*90%=3800
x*118%-(60000-x)*90%=3800
1.18x-(54000-0.9x)=3800
118%x-54000+90%x=3800
208%x=57800
208x=5780000
之後唔識計- -||
有好多小數點-0-唔知岩唔岩 = =?







３.)一個公事包標價$800,店主以15%折扣將公事包出售,若盈利百分率為15%.求公事包的成本。
800x85%/115%
=591.1......
４.)若以7折出售一個成本為$600的手袋後,仍能獲利40%,則標價應為多少?
600x140%/70%
=1200

我諗岩啦-0-
我f2-0-
第一題未教== ?

我都唔係好肯定 d題目問得衰 又唔多明中文題目 都幫下你


1.) No. of books sell :200 * 0.75 =150
let y be the cost of each book
the price of each book is 1.2y
Revenue: 1.2y * (150)

not sell yet: 200 - 150 = 50
refund: 50 * (0.95y )

Total cost : 150y +2.5y = 152.5y

Total lost: 50y - 50 * (0.95y ) = 2.5y

Total revenue = 1.2y * (150) = 180y

Profit = total revenue - total cost

2.) Cost = 60000
let Pa be the price of good A
let Ca be the cost of good A

1.18Ca = Pa

let Pb be the price of good B
let Cb be the cost of good B
0.9Cb = Pb

Profit = 3800

P= TR -TC
3800 = (1.18Ca +0.9Cb) - 60000

if we assume Pa = Pb because the question did tell us how much for each of them
so it will be Ca = P/1.18 and Cb = P/0.9, then

63800 = 2P
P =31900, Ca = 27033.898 , Cb = 35444.444

3.) Price = 800*.15 = 120 = TR
Profit = TR - TC
[( Profit - TC)/ TC] * 100% = 15%

0.15 TC + TC = Profit

1.15TC = 120 -TC
2.15TC = 120
TC = 55.814

4.) TC= Cost = 600
let P be the price of the bag
[( Profit - TC)/ TC] * 100% = 40%
Profit = TR - TC
Profit = 0.7P - TC

1.4TC = Profit

1.4TC = 0.7P -TC
1.4 (600) = 0.7P - 600
0.7P = 1440
P = 2057.143

1) 13.75%
2) 貨品A: $35000 貨品B: $25000
3) $591.3
4) $1200